diff --git a/config/log4j.properties b/config/log4j.properties
index 00f891cc5c6..b36d3e03cba 100644
--- a/config/log4j.properties
+++ b/config/log4j.properties
@@ -36,6 +36,12 @@ log4j.appender.requestAppender.File=kafka-request.log
 log4j.appender.requestAppender.layout=org.apache.log4j.PatternLayout
 log4j.appender.requestAppender.layout.ConversionPattern=[%d] %p %m (%c)%n
 
+log4j.appender.cleanerAppender=org.apache.log4j.DailyRollingFileAppender
+log4j.appender.cleanerAppender.DatePattern='.'yyyy-MM-dd-HH
+log4j.appender.cleanerAppender.File=log-cleaner.log
+log4j.appender.cleanerAppender.layout=org.apache.log4j.PatternLayout
+log4j.appender.cleanerAppender.layout.ConversionPattern=[%d] %p %m (%c)%n
+
 # Turn on all our debugging info
 #log4j.logger.kafka.producer.async.DefaultEventHandler=DEBUG, kafkaAppender
 #log4j.logger.kafka.client.ClientUtils=DEBUG, kafkaAppender
@@ -44,13 +50,18 @@ log4j.appender.requestAppender.layout.ConversionPattern=[%d] %p %m (%c)%n
 #log4j.logger.org.I0Itec.zkclient.ZkClient=DEBUG
 log4j.logger.kafka=INFO
 
-log4j.logger.kafka.network.RequestChannel$=TRACE, requestAppender
+log4j.logger.kafka.network.RequestChannel$=WARN, requestAppender
 log4j.additivity.kafka.network.RequestChannel$=false
 
 #log4j.logger.kafka.server.KafkaApis=TRACE, requestAppender
 #log4j.additivity.kafka.server.KafkaApis=false
-log4j.logger.kafka.request.logger=TRACE, requestAppender
+log4j.logger.kafka.request.logger=WARN, requestAppender
 log4j.additivity.kafka.request.logger=false
 
 log4j.logger.kafka.controller=TRACE, stateChangeAppender
 log4j.additivity.kafka.controller=false
+
+log4j.logger.kafka.log.LogCleaner=INFO, cleanerAppender
+log4j.additivity.kafka.log.LogCleaner=false
+log4j.logger.kafka.log.Cleaner=INFO, cleanerAppender
+log4j.additivity.kafka.log.Cleaner=false
diff --git a/config/server.properties b/config/server.properties
index 04408ddd8a7..5a16caf3332 100644
--- a/config/server.properties
+++ b/config/server.properties
@@ -114,3 +114,4 @@ kafka.csv.metrics.dir=/tmp/kafka_metrics
 # Disable csv reporting by default.
 kafka.csv.metrics.reporter.enabled=false
 
+log.cleanup.policy=delete
diff --git a/core/src/main/scala/kafka/cluster/Partition.scala b/core/src/main/scala/kafka/cluster/Partition.scala
index 71eb98096f2..af80631b4ec 100644
--- a/core/src/main/scala/kafka/cluster/Partition.scala
+++ b/core/src/main/scala/kafka/cluster/Partition.scala
@@ -23,7 +23,7 @@ import kafka.api.LeaderAndIsr
 import kafka.server.ReplicaManager
 import com.yammer.metrics.core.Gauge
 import kafka.metrics.KafkaMetricsGroup
-import kafka.common.ErrorMapping
+import kafka.common._
 import kafka.controller.{LeaderIsrAndControllerEpoch, KafkaController}
 
 
@@ -75,11 +75,11 @@ class Partition(val topic: String,
       case None =>
         if (isReplicaLocal(replicaId)) {
           val log = logManager.getOrCreateLog(topic, partitionId)
-          val offset = replicaManager.highWatermarkCheckpoints(log.dir.getParent).read(topic, partitionId).min(log.logEndOffset)
+          val checkpoint = replicaManager.highWatermarkCheckpoints(log.dir.getParent) 
+          val offset = checkpoint.read.getOrElse(TopicAndPartition(topic, partitionId), 0L).min(log.logEndOffset)
           val localReplica = new Replica(replicaId, this, time, offset, Some(log))
           addReplicaIfNotExists(localReplica)
-        }
-        else {
+        } else {
           val remoteReplica = new Replica(replicaId, this, time)
           addReplicaIfNotExists(remoteReplica)
         }
diff --git a/core/src/main/scala/kafka/common/OptimisticLockFailureException.scala b/core/src/main/scala/kafka/common/OptimisticLockFailureException.scala
new file mode 100644
index 00000000000..0e69110e716
--- /dev/null
+++ b/core/src/main/scala/kafka/common/OptimisticLockFailureException.scala
@@ -0,0 +1,23 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.common
+
+/**
+ * Thrown when an optimistic locking attempt receives concurrent modifications
+ */
+class OptimisticLockFailureException(message: String) extends RuntimeException(message)
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/log/CleanerConfig.scala b/core/src/main/scala/kafka/log/CleanerConfig.scala
new file mode 100644
index 00000000000..999fee868c1
--- /dev/null
+++ b/core/src/main/scala/kafka/log/CleanerConfig.scala
@@ -0,0 +1,41 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+/**
+ * Configuration parameters for the log cleaner
+ * 
+ * @param numThreads The number of cleaner threads to run
+ * @param dedupeBufferSize The total memory used for log deduplication
+ * @param dedupeBufferLoadFactor The maximum percent full for the deduplication buffer
+ * @param maxMessageSize The maximum size of a message that can appear in the log
+ * @param maxIoBytesPerSecond The maximum read and write I/O that all cleaner threads are allowed to do
+ * @param backOffMs The amount of time to wait before rechecking if no logs are eligible for cleaning
+ * @param enableCleaner Allows completely disabling the log cleaner
+ * @param hashAlgorithm The hash algorithm to use in key comparison.
+ */
+case class CleanerConfig(val numThreads: Int = 1, 
+                         val dedupeBufferSize: Int = 4*1024*1024,
+                         val dedupeBufferLoadFactor: Double = 0.75,
+                         val ioBufferSize: Int = 1024*1024,
+                         val maxMessageSize: Int = 32*1024*1024,
+                         val maxIoBytesPerSecond: Double = Double.MaxValue,
+                         val backOffMs: Long = 60 * 1000,
+                         val enableCleaner: Boolean = true,
+                         val hashAlgorithm: String = "MD5") {
+}
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/log/FileMessageSet.scala b/core/src/main/scala/kafka/log/FileMessageSet.scala
index 37e8d87401a..a74abfef53d 100644
--- a/core/src/main/scala/kafka/log/FileMessageSet.scala
+++ b/core/src/main/scala/kafka/log/FileMessageSet.scala
@@ -38,7 +38,7 @@ import kafka.metrics.{KafkaTimer, KafkaMetricsGroup}
  * @param isSlice Should the start and end parameters be used for slicing?
  */
 @nonthreadsafe
-class FileMessageSet private[kafka](val file: File,
+class FileMessageSet private[kafka](@volatile var file: File,
                                     private[log] val channel: FileChannel,
                                     private[log] val start: Int,
                                     private[log] val end: Int,
@@ -223,14 +223,36 @@ class FileMessageSet private[kafka](val file: File,
    * Truncate this file message set to the given size in bytes. Note that this API does no checking that the 
    * given size falls on a valid message boundary.
    * @param targetSize The size to truncate to.
+   * @return The number of bytes truncated off
    */
-  def truncateTo(targetSize: Int) = {
-    if(targetSize > sizeInBytes || targetSize < 0)
+  def truncateTo(targetSize: Int): Int = {
+    val originalSize = sizeInBytes
+    if(targetSize > originalSize || targetSize < 0)
       throw new KafkaException("Attempt to truncate log segment to " + targetSize + " bytes failed, " +
-                               " size of this log segment is " + sizeInBytes + " bytes.")
+                               " size of this log segment is " + originalSize + " bytes.")
     channel.truncate(targetSize)
     channel.position(targetSize)
     _size.set(targetSize)
+    originalSize - targetSize
+  }
+  
+  /**
+   * Read from the underlying file into the buffer starting at the given position
+   */
+  def readInto(buffer: ByteBuffer, position: Int): ByteBuffer = {
+    channel.read(buffer, position)
+    buffer.flip()
+    buffer
+  }
+  
+  /**
+   * Rename the file that backs this message set
+   * @return true iff the rename was successful
+   */
+  def renameTo(f: File): Boolean = {
+    val success = this.file.renameTo(f)
+    this.file = f
+    success
   }
   
 }
diff --git a/core/src/main/scala/kafka/log/Log.scala b/core/src/main/scala/kafka/log/Log.scala
index 5ea94890005..ac12b74c0e5 100644
--- a/core/src/main/scala/kafka/log/Log.scala
+++ b/core/src/main/scala/kafka/log/Log.scala
@@ -49,15 +49,9 @@ import com.yammer.metrics.core.Gauge
  */
 @threadsafe
 class Log(val dir: File,
+          val config: LogConfig,
+          val needsRecovery: Boolean,
           val scheduler: Scheduler,
-          val maxSegmentSize: Int,
-          val maxMessageSize: Int, 
-          val flushInterval: Int = Int.MaxValue,
-          val rollIntervalMs: Long = Long.MaxValue, 
-          val needsRecovery: Boolean, 
-          val maxIndexSize: Int = (10*1024*1024),
-          val indexIntervalBytes: Int = 4096,
-          val segmentDeleteDelayMs: Long = 60000,
           time: Time = SystemTime) extends Logging with KafkaMetricsGroup {
 
   import kafka.log.Log._
@@ -73,6 +67,9 @@ class Log(val dir: File,
 
   /* the actual segments of the log */
   private val segments: ConcurrentNavigableMap[Long,LogSegment] = loadSegments()
+  
+  /* The number of times the log has been truncated */
+  private val truncates = new AtomicInteger(0)
     
   /* Calculate the offset of the next message */
   private val nextOffset: AtomicLong = new AtomicLong(activeSegment.nextOffset())
@@ -90,58 +87,82 @@ class Log(val dir: File,
   private def loadSegments(): ConcurrentNavigableMap[Long, LogSegment] = {
     // open all the segments read-only
     val logSegments = new ConcurrentSkipListMap[Long, LogSegment]
-    val ls = dir.listFiles()
-    if(ls != null) {
-      for(file <- ls if file.isFile) {
-        if(!file.canRead)
-          throw new IOException("Could not read file " + file)
-        val filename = file.getName
-        if(filename.endsWith(DeletedFileSuffix)) {
-          // if the file ends in .deleted, delete it
-          val deleted = file.delete()
-          if(!deleted)
-            warn("Attempt to delete defunct segment file %s failed.".format(filename))
-        }  else if(filename.endsWith(IndexFileSuffix)) {
-          // if it is an index file, make sure it has a corresponding .log file
-          val logFile = new File(file.getAbsolutePath.replace(IndexFileSuffix, LogFileSuffix))
-          if(!logFile.exists) {
-            warn("Found an orphaned index file, %s, with no corresponding log file.".format(file.getAbsolutePath))
-            file.delete()
-          }
-        } else if(filename.endsWith(LogFileSuffix)) {
-          // if its a log file, load the corresponding log segment
-          val start = filename.substring(0, filename.length - LogFileSuffix.length).toLong
-          val hasIndex = Log.indexFilename(dir, start).exists
-          val segment = new LogSegment(dir = dir, 
-                                       startOffset = start,
-                                       indexIntervalBytes = indexIntervalBytes, 
-                                       maxIndexSize = maxIndexSize)
-          if(!hasIndex) {
-            // this can only happen if someone manually deletes the index file
-            error("Could not find index file corresponding to log file %s, rebuilding index...".format(segment.log.file.getAbsolutePath))
-            segment.recover(maxMessageSize)
-          }
-          logSegments.put(start, segment)
+
+    // create the log directory if it doesn't exist
+    dir.mkdirs()
+    
+    // first do a pass through the files in the log directory and remove any temporary files 
+    // and complete any interrupted swap operations
+    for(file <- dir.listFiles if file.isFile) {
+      if(!file.canRead)
+        throw new IOException("Could not read file " + file)
+      val filename = file.getName
+      if(filename.endsWith(DeletedFileSuffix) || filename.endsWith(CleanedFileSuffix)) {
+        // if the file ends in .deleted or .cleaned, delete it
+        file.delete()
+      } else if(filename.endsWith(SwapFileSuffix)) {
+        // we crashed in the middle of a swap operation, to recover:
+        // if a log, swap it in and delete the .index file
+        // if an index just delete it, it will be rebuilt
+        val baseName = new File(Utils.replaceSuffix(file.getPath, SwapFileSuffix, ""))
+        if(baseName.getPath.endsWith(IndexFileSuffix)) {
+          file.delete()
+        } else if(baseName.getPath.endsWith(LogFileSuffix)){
+          // delete the index
+          val index = new File(Utils.replaceSuffix(baseName.getPath, LogFileSuffix, IndexFileSuffix))
+          index.delete()
+          // complete the swap operation
+          val renamed = file.renameTo(baseName)
+          if(renamed)
+            info("Found log file %s from interrupted swap operation, repairing.".format(file.getPath))
+          else
+            throw new KafkaException("Failed to rename file %s.".format(file.getPath))
         }
       }
     }
 
+    // now do a second pass and load all the .log and .index files
+    for(file <- dir.listFiles if file.isFile) {
+      val filename = file.getName
+      if(filename.endsWith(IndexFileSuffix)) {
+        // if it is an index file, make sure it has a corresponding .log file
+        val logFile = new File(file.getAbsolutePath.replace(IndexFileSuffix, LogFileSuffix))
+        if(!logFile.exists) {
+          warn("Found an orphaned index file, %s, with no corresponding log file.".format(file.getAbsolutePath))
+          file.delete()
+        }
+      } else if(filename.endsWith(LogFileSuffix)) {
+        // if its a log file, load the corresponding log segment
+        val start = filename.substring(0, filename.length - LogFileSuffix.length).toLong
+        val hasIndex = Log.indexFilename(dir, start).exists
+        val segment = new LogSegment(dir = dir, 
+                                     startOffset = start,
+                                     indexIntervalBytes = config.indexInterval, 
+                                     maxIndexSize = config.maxIndexSize)
+        if(!hasIndex) {
+          error("Could not find index file corresponding to log file %s, rebuilding index...".format(segment.log.file.getAbsolutePath))
+          segment.recover(config.maxMessageSize)
+        }
+        logSegments.put(start, segment)
+      }
+    }
+
     if(logSegments.size == 0) {
       // no existing segments, create a new mutable segment beginning at offset 0
       logSegments.put(0,
                       new LogSegment(dir = dir, 
                                      startOffset = 0,
-                                     indexIntervalBytes = indexIntervalBytes, 
-                                     maxIndexSize = maxIndexSize))
+                                     indexIntervalBytes = config.indexInterval, 
+                                     maxIndexSize = config.maxIndexSize))
     } else {
       // reset the index size of the currently active log segment to allow more entries
       val active = logSegments.lastEntry.getValue
-      active.index.resize(maxIndexSize)
+      active.index.resize(config.maxIndexSize)
 
       // run recovery on the active segment if necessary
       if(needsRecovery) {
         info("Recovering active segment of %s.".format(name))
-        active.recover(maxMessageSize)
+        active.recover(config.maxMessageSize)
       }
     }
     logSegments
@@ -152,6 +173,11 @@ class Log(val dir: File,
    * Take care! this is an O(n) operation.
    */
   def numberOfSegments: Int = segments.size
+  
+  /**
+   * The number of truncates that have occurred since the log was opened.
+   */
+  def numberOfTruncates: Int = truncates.get
 
   /**
    * Close this log
@@ -194,22 +220,24 @@ class Log(val dir: File,
         val segment = maybeRoll()
           
         if(assignOffsets) {
-           // assign offsets to the messageset
+          // assign offsets to the messageset
           appendInfo.firstOffset = nextOffset.get
-          val offsetCounter = new AtomicLong(nextOffset.get)
-          validMessages = validMessages.assignOffsets(offsetCounter, appendInfo.codec)
-          appendInfo.lastOffset = offsetCounter.get - 1
+          val offset = new AtomicLong(nextOffset.get)
+          validMessages = validMessages.assignOffsets(offset, appendInfo.codec)
+          appendInfo.lastOffset = offset.get - 1
         } else {
           // we are taking the offsets we are given
           if(!appendInfo.offsetsMonotonic || appendInfo.firstOffset < nextOffset.get)
-              throw new IllegalArgumentException("Out of order offsets found in " + messages)
+            throw new IllegalArgumentException("Out of order offsets found in " + messages)
         }
 
         // now append to the log
         trace("Appending message set to %s with offsets %d to %d.".format(name, appendInfo.firstOffset, appendInfo.lastOffset))
         segment.append(appendInfo.firstOffset, validMessages)
+        
+        // increment the log end offset
         nextOffset.set(appendInfo.lastOffset + 1)
-
+          
         // maybe flush the log and index
         maybeFlush(appendInfo.count)
         
@@ -263,8 +291,8 @@ class Log(val dir: File,
       // check the validity of the message by checking CRC and message size
       val m = messageAndOffset.message
       m.ensureValid()
-      if(MessageSet.entrySize(m) > maxMessageSize)
-        throw new MessageSizeTooLargeException("Message size is %d bytes which exceeds the maximum configured message size of %d.".format(MessageSet.entrySize(m), maxMessageSize))
+      if(MessageSet.entrySize(m) > config.maxMessageSize)
+        throw new MessageSizeTooLargeException("Message size is %d bytes which exceeds the maximum configured message size of %d.".format(MessageSet.entrySize(m), config.maxMessageSize))
       
       messageCount += 1;
       
@@ -372,18 +400,21 @@ class Log(val dir: File,
    */
   private def maybeRoll(): LogSegment = {
     val segment = activeSegment
-    if (segment.size > maxSegmentSize) {
-      info("Rolling %s due to full data log".format(name))
-      roll()
-    } else if (segment.size > 0 && time.milliseconds - segment.created > rollIntervalMs) {
-      info("Rolling %s due to time based rolling".format(name))
-      roll()
-    } else if (segment.index.isFull) {
-      info("Rolling %s due to full index maxIndexSize = %d, entries = %d, maxEntries = %d"
-        .format(name, segment.index.maxIndexSize, segment.index.entries(), segment.index.maxEntries))
+    if (segment.size > config.segmentSize || 
+        segment.size > 0 && time.milliseconds - segment.created > config.segmentMs ||
+        segment.index.isFull) {
+      debug("Rolling new log segment in %s (log_size = %d/%d, index_size = %d/%d, age_ms = %d/%d)."
+            .format(name,
+                    segment.size,
+                    config.segmentSize,
+                    segment.index.entries,
+                    segment.index.maxEntries,
+                    time.milliseconds - segment.created,
+                    config.segmentMs))
       roll()
-    } else
+    } else {
       segment
+    }
   }
   
   /**
@@ -412,11 +443,11 @@ class Log(val dir: File,
       }
       val segment = new LogSegment(dir, 
                                    startOffset = newOffset,
-                                   indexIntervalBytes = indexIntervalBytes, 
-                                   maxIndexSize = maxIndexSize)
-      val prev = segments.put(segment.baseOffset, segment)
+                                   indexIntervalBytes = config.indexInterval, 
+                                   maxIndexSize = config.maxIndexSize)
+      val prev = addSegment(segment)
       if(prev != null)
-        throw new KafkaException("Trying to roll a new log segment for topic partition %s with start offset %d while it already exists.".format(dir.getName, newOffset))
+        throw new KafkaException("Trying to roll a new log segment for topic partition %s with start offset %d while it already exists.".format(name, newOffset))
       segment
     }
   }
@@ -426,12 +457,12 @@ class Log(val dir: File,
    * @param numberOfMessages The number of messages that are being appended
    */
   private def maybeFlush(numberOfMessages : Int) {
-    if(unflushed.addAndGet(numberOfMessages) >= flushInterval)
+    if(unflushed.addAndGet(numberOfMessages) >= config.flushInterval)
       flush()
   }
 
   /**
-   * Flush this log file and assoicated index to the physical disk
+   * Flush this log file and associated index to the physical disk
    */
   def flush() : Unit = {
     if (unflushed.get == 0)
@@ -475,6 +506,7 @@ class Log(val dir: File,
         activeSegment.truncateTo(targetOffset)
         this.nextOffset.set(targetOffset)
       }
+      truncates.getAndIncrement
     }
   }
     
@@ -487,12 +519,12 @@ class Log(val dir: File,
     lock synchronized {
       val segmentsToDelete = logSegments.toList
       segmentsToDelete.foreach(deleteSegment(_))
-      segments.put(newOffset, 
-                   new LogSegment(dir, 
-                                  newOffset,
-                                  indexIntervalBytes = indexIntervalBytes, 
-                                  maxIndexSize = maxIndexSize))
+      addSegment(new LogSegment(dir, 
+                                newOffset,
+                                indexIntervalBytes = config.indexInterval, 
+                                maxIndexSize = config.maxIndexSize))
       this.nextOffset.set(newOffset)
+      truncates.getAndIncrement
     }
   }
 
@@ -511,7 +543,13 @@ class Log(val dir: File,
    */
   def logSegments: Iterable[LogSegment] = asIterable(segments.values)
   
-  override def toString() = "Log(" + this.dir + ")"
+  /**
+   * Get all segments beginning with the segment that includes "from" and ending with the segment
+   * that includes up to "to-1" or the end of the log (if to > logEndOffset)
+   */
+  def logSegments(from: Long, to: Long) = asIterable(segments.subMap(from, true, to, false).values)
+  
+  override def toString() = "Log(" + dir + ")"
   
   /**
    * This method performs an asynchronous log segment delete by doing the following:
@@ -526,37 +564,82 @@ class Log(val dir: File,
    * @param segment The log segment to schedule for deletion
    */
   private def deleteSegment(segment: LogSegment) {
-    info("Scheduling log segment %d for log %s for deletion.".format(segment.baseOffset, dir.getName))
+    info("Scheduling log segment %d for log %s for deletion.".format(segment.baseOffset, name))
     lock synchronized {
       segments.remove(segment.baseOffset)
-      val deletedLog = new File(segment.log.file.getPath + Log.DeletedFileSuffix)
-      val deletedIndex = new File(segment.index.file.getPath + Log.DeletedFileSuffix)
-      val renamedLog = segment.log.file.renameTo(deletedLog)
-      val renamedIndex = segment.index.file.renameTo(deletedIndex)
-      if(!renamedLog && segment.log.file.exists)
-        throw new KafkaStorageException("Failed to rename file %s to %s for log %s.".format(segment.log.file.getPath, deletedLog.getPath, name))
-      if(!renamedIndex && segment.index.file.exists)
-        throw new KafkaStorageException("Failed to rename file %s to %s for log %s.".format(segment.index.file.getPath, deletedIndex.getPath, name))
-      def asyncDeleteFiles() {
-        info("Deleting log segment %s for log %s.".format(segment.baseOffset, name))
-        if(!deletedLog.delete())
-          warn("Failed to delete log segment file %s for log %s.".format(deletedLog.getPath, name))
-        if(!deletedIndex.delete())
-          warn("Failed to delete index segment file %s for log %s.".format(deletedLog.getPath, name))
-      }
-      scheduler.schedule("delete-log-segment", asyncDeleteFiles, delay = segmentDeleteDelayMs)
+      asyncDeleteSegment(segment)
+    }
+  }
+  
+  /**
+   * Perform an asynchronous delete on the given file if it exists (otherwise do nothing)
+   * @throws KafkaStorageException if the file can't be renamed and still exists 
+   */
+  private def asyncDeleteSegment(segment: LogSegment) {
+    segment.changeFileSuffixes("", Log.DeletedFileSuffix)
+    def deleteSeg() {
+      info("Deleting segment %d from log %s.".format(segment.baseOffset, name))
+      segment.delete()
     }
+    scheduler.schedule("delete-file", deleteSeg, delay = config.fileDeleteDelayMs)
+  }
+  
+  /**
+   * Swap a new segment in place and delete one or more existing segments in a crash-safe manner. The old segments will
+   * be asynchronously deleted.
+   * 
+   * @param newSegment The new log segment to add to the log
+   * @param oldSegments The old log segments to delete from the log
+   */
+  private[log] def replaceSegments(newSegment: LogSegment, oldSegments: Seq[LogSegment], expectedTruncates: Int) {
+    lock synchronized {
+      if(expectedTruncates != numberOfTruncates)
+        throw new OptimisticLockFailureException("The log has been truncated, expected %d but found %d.".format(expectedTruncates, numberOfTruncates))
+      // need to do this in two phases to be crash safe AND do the delete asynchronously
+      // if we crash in the middle of this we complete the swap in loadSegments()
+      newSegment.changeFileSuffixes(Log.CleanedFileSuffix, Log.SwapFileSuffix)
+      addSegment(newSegment)
+        
+      // delete the old files
+      for(seg <- oldSegments) {
+        // remove the index entry
+        if(seg.baseOffset != newSegment.baseOffset)
+          segments.remove(seg.baseOffset)
+        // delete segment
+        asyncDeleteSegment(seg)
+      }
+      // okay we are safe now, remove the swap suffix
+      newSegment.changeFileSuffixes(Log.SwapFileSuffix, "")
+    }  
   }
   
+  /**
+   * Add the given segment to the segments in this log. If this segment replaces an existing segment, delete it.
+   * @param segment The segment to add
+   */
+  def addSegment(segment: LogSegment) = this.segments.put(segment.baseOffset, segment)
+  
 }
 
 /**
  * Helper functions for logs
  */
 object Log {
+  
+  /** a log file */
   val LogFileSuffix = ".log"
+    
+  /** an index file */
   val IndexFileSuffix = ".index"
+    
+  /** a file that is scheduled to be deleted */
   val DeletedFileSuffix = ".deleted"
+    
+  /** A temporary file that is being used for log cleaning */
+  val CleanedFileSuffix = ".cleaned"
+    
+  /** A temporary file used when swapping files into the log */
+  val SwapFileSuffix = ".swap"
 
   /**
    * Make log segment file name from offset bytes. All this does is pad out the offset number with zeros
diff --git a/core/src/main/scala/kafka/log/LogCleaner.scala b/core/src/main/scala/kafka/log/LogCleaner.scala
new file mode 100644
index 00000000000..368a12be1f9
--- /dev/null
+++ b/core/src/main/scala/kafka/log/LogCleaner.scala
@@ -0,0 +1,557 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+import scala.collection._
+import scala.math
+import java.nio._
+import java.util.concurrent.Semaphore
+import java.util.concurrent.TimeUnit
+import java.util.concurrent.atomic._
+import java.io.File
+import kafka.common._
+import kafka.message._
+import kafka.server.OffsetCheckpoint
+import kafka.utils._
+
+/**
+ * The cleaner is responsible for removing obsolete records from logs which have the dedupe retention strategy.
+ * A message with key K and offset O is obsolete if there exists a message with key K and offset O' such that O < O'.
+ * 
+ * Each log can be thought of being split into two sections of segments: a "clean" section which has previously been cleaned followed by a
+ * "dirty" section that has not yet been cleaned. The active log segment is always excluded from cleaning.
+ *
+ * The cleaning is carried out by a pool of background threads. Each thread chooses the dirtiest log that has the "dedupe" retention policy 
+ * and cleans that. The dirtiness of the log is guessed by taking the ratio of bytes in the dirty section of the log to the total bytes in the log. 
+ * 
+ * To clean a log the cleaner first builds a mapping of key=>last_offset for the dirty section of the log. For memory efficiency this mapping
+ * is approximate. That is allowed to lose some key=>offset pairs, but never to return a wrong answer. See kafka.log.OffsetMap for details of
+ * the implementation of the mapping. 
+ * 
+ * Once the key=>offset map is built, the log is cleaned by recopying each log segment but omitting any key that appears in the offset map with a 
+ * higher offset than what is found in the segment (i.e. messages with a key that appears in the dirty section of the log).
+ * 
+ * To avoid segments shrinking to very small sizes with repeated cleanings we implement a rule by which if we will merge successive segments when
+ * doing a cleaning if their log and index size are less than the maximum log and index size prior to the clean beginning.
+ * 
+ * Cleaned segments are swapped into the log as they become available.
+ * 
+ * One nuance that the cleaner must handle is log truncation. If a log is truncated while it is being cleaned the cleaning of that log is aborted.
+ * 
+ * @param config Configuration parameters for the cleaner
+ * @param logDirs The directories where offset checkpoints reside
+ * @param logs The pool of logs
+ * @param time A way to control the passage of time
+ */
+class LogCleaner(val config: CleanerConfig,
+                 val logDirs: Array[File],
+                 val logs: Pool[TopicAndPartition, Log], 
+                 time: Time = SystemTime) extends Logging {
+  
+  /* the offset checkpoints holding the last cleaned point for each log */
+  private val checkpoints = logDirs.map(dir => (dir, new OffsetCheckpoint(new File(dir, "cleaner-offset-checkpoint")))).toMap
+  
+  /* the set of logs currently being cleaned */
+  private val inProgress = mutable.HashSet[TopicAndPartition]()
+  
+  /* a global lock used to control all access to the in-progress set and the offset checkpoints */
+  private val lock = new Object
+    
+  /* a counter for creating unique thread names*/
+  private val threadId = new AtomicInteger(0)
+  
+  /* a throttle used to limit the I/O of all the cleaner threads to a user-specified maximum rate */
+  private val throttler = new Throttler(desiredRatePerSec = config.maxIoBytesPerSecond, 
+                                        checkIntervalMs = 300, 
+                                        throttleDown = true, 
+                                        time = time)
+  
+  /* the threads */
+  private val cleaners = (0 until config.numThreads).map(_ => new CleanerThread())
+  
+  /* a hook for testing to synchronize on log cleaning completions */
+  private val cleaned = new Semaphore(0)
+  
+  /**
+   * Start the background cleaning
+   */
+  def startup() {
+    info("Starting the log cleaner")
+    cleaners.foreach(_.start())
+  }
+  
+  /**
+   * Stop the background cleaning
+   */
+  def shutdown() {
+    info("Shutting down the log cleaner.")
+    cleaners.foreach(_.interrupt())
+    cleaners.foreach(_.join())
+  }
+  
+  /**
+   * For testing, a way to know when work has completed. This method blocks until the 
+   * cleaner has processed up to the given offset on the specified topic/partition
+   */
+  def awaitCleaned(topic: String, part: Int, offset: Long, timeout: Long = 30000L): Unit = {
+    while(!allCleanerCheckpoints.contains(TopicAndPartition(topic, part)))
+      cleaned.tryAcquire(timeout, TimeUnit.MILLISECONDS)
+  }
+  
+  /**
+   * @return the position processed for all logs.
+   */
+  def allCleanerCheckpoints(): Map[TopicAndPartition, Long] = 
+    checkpoints.values.flatMap(_.read()).toMap
+  
+   /**
+    * Choose the log to clean next and add it to the in-progress set. We recompute this
+    * every time off the full set of logs to allow logs to be dynamically added to the pool of logs
+    * the log manager maintains.
+    */
+  private def grabFilthiestLog(): Option[LogToClean] = {
+    lock synchronized {
+      val lastClean = allCleanerCheckpoints()      
+      val cleanableLogs = logs.filter(l => l._2.config.dedupe)                                     // skip any logs marked for delete rather than dedupe
+                              .filterNot(l => inProgress.contains(l._1))                           // skip any logs already in-progress
+                              .map(l => LogToClean(l._1, l._2, lastClean.getOrElse(l._1, 0)))      // create a LogToClean instance for each
+      val dirtyLogs = cleanableLogs.filter(l => l.totalBytes > 0)                                  // must have some bytes
+                                   .filter(l => l.cleanableRatio > l.log.config.minCleanableRatio) // and must meet the minimum threshold for dirty byte ratio
+      if(dirtyLogs.isEmpty) {
+        None
+      } else {
+        val filthiest = dirtyLogs.max
+        inProgress += filthiest.topicPartition
+        Some(filthiest)
+      }
+    }
+  }
+  
+  /**
+   * Save out the endOffset and remove the given log from the in-progress set.
+   */
+  private def doneCleaning(topicAndPartition: TopicAndPartition, dataDir: File, endOffset: Long) {
+    lock synchronized {
+      val checkpoint = checkpoints(dataDir)
+      val offsets = checkpoint.read() + ((topicAndPartition, endOffset))
+      checkpoint.write(offsets)
+      inProgress -= topicAndPartition
+    }
+    cleaned.release()
+  }
+
+  /**
+   * The cleaner threads do the actual log cleaning. Each thread processes does its cleaning repeatedly by
+   * choosing the dirtiest log, cleaning it, and then swapping in the cleaned segments.
+   */
+  private class CleanerThread extends Thread {
+    val cleaner = new Cleaner(id = threadId.getAndIncrement(),
+                              offsetMap = new SkimpyOffsetMap(memory = config.dedupeBufferSize / config.numThreads, 
+                                                              maxLoadFactor = config.dedupeBufferLoadFactor, 
+                                                              hashAlgorithm = config.hashAlgorithm),
+                              ioBufferSize = config.ioBufferSize / config.numThreads / 2,
+                              maxIoBufferSize = config.maxMessageSize,
+                              throttler = throttler,
+                              time = time)
+    
+    setName("kafka-log-cleaner-thread-" + cleaner.id)
+    setDaemon(false)
+
+    /**
+     * The main loop for the cleaner thread
+     */
+    override def run() {
+      info("Starting cleaner thread %d...".format(cleaner.id))
+      try {
+        while(!isInterrupted) {
+          cleanOrSleep()
+        }
+      } catch {
+        case e: InterruptedException => // all done
+        case e: Exception =>
+          error("Error in cleaner thread %d:".format(cleaner.id), e)
+      }
+      info("Shutting down cleaner thread %d.".format(cleaner.id))
+    }
+    
+    /**
+     * Clean a log if there is a dirty log available, otherwise sleep for a bit
+     */
+    private def cleanOrSleep() {
+      grabFilthiestLog() match {
+        case None =>
+          // there are no cleanable logs, sleep a while
+          time.sleep(config.backOffMs)
+        case Some(cleanable) =>
+          // there's a log, clean it
+          var endOffset = cleanable.firstDirtyOffset
+          try {
+            endOffset = cleaner.clean(cleanable)
+            logStats(cleaner.id, cleanable.log.name, cleanable.firstDirtyOffset, endOffset, cleaner.stats)
+          } catch {
+            case e: OptimisticLockFailureException => 
+              info("Cleaning of log was aborted due to colliding truncate operation.")
+          } finally {
+            doneCleaning(cleanable.topicPartition, cleanable.log.dir.getParentFile, endOffset)
+          }
+      }
+    }
+    
+    /**
+     * Log out statistics on a single run of the cleaner.
+     */
+    def logStats(id: Int, name: String, from: Long, to: Long, stats: CleanerStats) {
+      def mb(bytes: Double) = bytes / (1024*1024)
+      val message = 
+        "%n\tLog cleaner %d cleaned log %s (dirty section = [%d, %d])%n".format(id, name, from, to) + 
+        "\t%,.1f MB of log processed in %,.1f seconds (%,.1f MB/sec).%n".format(mb(stats.bytesRead), 
+                                                                                stats.elapsedSecs, 
+                                                                                mb(stats.bytesRead/stats.elapsedSecs)) + 
+        "\tIndexed %,.1f MB in %.1f seconds (%,.1f Mb/sec, %.1f%% of total time)%n".format(mb(stats.mapBytesRead), 
+                                                                                           stats.elapsedIndexSecs, 
+                                                                                           mb(stats.mapBytesRead)/stats.elapsedIndexSecs, 
+                                                                                           100 * stats.elapsedIndexSecs.toDouble/stats.elapsedSecs) + 
+        "\tCleaned %,.1f MB in %.1f seconds (%,.1f Mb/sec, %.1f%% of total time)%n".format(mb(stats.bytesRead), 
+                                                                                           stats.elapsedSecs - stats.elapsedIndexSecs, 
+                                                                                           mb(stats.bytesRead)/(stats.elapsedSecs - stats.elapsedIndexSecs), 100 * (stats.elapsedSecs - stats.elapsedIndexSecs).toDouble/stats.elapsedSecs) + 
+        "\tStart size: %,.1f MB (%,d messages)%n".format(mb(stats.bytesRead), stats.messagesRead) +
+        "\tEnd size: %,.1f MB (%,d messages)%n".format(mb(stats.bytesWritten), stats.messagesWritten) + 
+        "\t%.1f%% size reduction (%.1f%% fewer messages)%n".format(100.0 * (1.0 - stats.bytesWritten.toDouble/stats.bytesRead), 
+                                                                   100.0 * (1.0 - stats.messagesWritten.toDouble/stats.messagesRead))
+      info(message)
+    }
+   
+  }
+}
+
+/**
+ * This class holds the actual logic for cleaning a log
+ * @param id An identifier used for logging
+ * @param offsetMap The map used for deduplication
+ * @param bufferSize The size of the buffers to use. Memory usage will be 2x this number as there is a read and write buffer.
+ * @param throttler The throttler instance to use for limiting I/O rate.
+ * @param time The time instance
+ */
+private[log] class Cleaner(val id: Int,
+                           offsetMap: OffsetMap,
+                           ioBufferSize: Int,
+                           maxIoBufferSize: Int,
+                           throttler: Throttler,
+                           time: Time) extends Logging {
+
+  this.logIdent = "Cleaner " + id + ":"
+  val stats = new CleanerStats(time)
+  private var readBuffer = ByteBuffer.allocate(ioBufferSize) // buffer for disk read I/O
+  private var writeBuffer = ByteBuffer.allocate(ioBufferSize) // buffer for disk write I/O
+
+  /**
+   * Clean the given log
+   *
+   * @param cleanable The log to be cleaned
+   *
+   * @return The first offset not cleaned
+   */
+  private[log] def clean(cleanable: LogToClean): Long = {
+    stats.clear()
+    val topic = cleanable.topicPartition.topic
+    val part = cleanable.topicPartition.partition
+    info("Beginning cleaning of %s-%d.".format(topic, part))
+    val log = cleanable.log
+    val truncateCount = log.numberOfTruncates
+    
+    // build the offset map
+    val upperBoundOffset = math.min(log.activeSegment.baseOffset, cleanable.firstDirtyOffset + offsetMap.capacity)
+    val endOffset = buildOffsetMap(log, cleanable.firstDirtyOffset, upperBoundOffset, offsetMap) + 1
+    stats.indexDone()
+    
+    // group the segments and clean the groups
+    for (group <- groupSegmentsBySize(log.logSegments(0, endOffset), log.config.segmentSize, log.config.maxIndexSize)) {
+      info("Cleaning segments %s for log %s...".format(group.map(_.baseOffset).mkString(","), log.name))
+      cleanSegments(log, group, offsetMap, truncateCount)
+    }
+    stats.allDone()
+    endOffset
+  }
+
+  /**
+   * Clean a group of segments into a single replacement segment
+   *
+   * @param log The log being cleaned
+   * @param segments The group of segments being cleaned
+   * @param map The offset map to use for cleaning segments
+   * @param expectedTruncateCount A count used to check if the log is being truncated and rewritten under our feet
+   */
+  private[log] def cleanSegments(log: Log, segments: Seq[LogSegment], map: OffsetMap, expectedTruncateCount: Int) {
+    // create a new segment with the suffix .cleaned appended to both the log and index name
+    val logFile = new File(segments.head.log.file.getPath + Log.CleanedFileSuffix)
+    logFile.delete()
+    val indexFile = new File(segments.head.index.file.getPath + Log.CleanedFileSuffix)
+    indexFile.delete()
+    val messages = new FileMessageSet(logFile)
+    val index = new OffsetIndex(indexFile, segments.head.baseOffset, segments.head.index.maxIndexSize)
+    val cleaned = new LogSegment(messages, index, segments.head.baseOffset, segments.head.indexIntervalBytes, time)
+
+    // clean segments into the new destination segment
+    for (old <- segments)
+      cleanInto(old, cleaned, map)
+      
+    // trim excess index
+    index.trimToValidSize()
+    
+    // flush new segment to disk before swap
+    cleaned.flush()
+
+    // swap in new segment  
+    info("Swapping in cleaned segment %d for %s in log %s.".format(cleaned.baseOffset, segments.map(_.baseOffset).mkString(","), log.name))
+    try {
+      log.replaceSegments(cleaned, segments, expectedTruncateCount)
+    } catch {
+      case e: OptimisticLockFailureException =>
+        cleaned.delete()
+        throw e  
+    }
+  }
+
+  /**
+   * Clean the given source log segment into the destination segment using the key=>offset mapping
+   * provided
+   *
+   * @param source The dirty log segment
+   * @param dest The cleaned log segment
+   * @param map The key=>offset mapping
+   *
+   * TODO: Implement proper compression support
+   */
+  private[log] def cleanInto(source: LogSegment, dest: LogSegment, map: OffsetMap) {
+    var position = 0
+    while (position < source.log.sizeInBytes) {
+      checkDone()
+      // read a chunk of messages and copy any that are to be retained to the write buffer to be written out
+      readBuffer.clear()
+      writeBuffer.clear()
+      val messages = new ByteBufferMessageSet(source.log.readInto(readBuffer, position))
+      throttler.maybeThrottle(messages.sizeInBytes)
+      // check each message to see if it is to be retained
+      var messagesRead = 0
+      for (entry <- messages) {
+        messagesRead += 1
+        val size = MessageSet.entrySize(entry.message)
+        position += size
+        stats.readMessage(size)
+        val key = entry.message.key
+        require(key != null, "Found null key in log segment %s which is marked as dedupe.".format(source.log.file.getAbsolutePath))
+        val lastOffset = map.get(key)
+        /* retain the record if it isn't present in the map OR it is present but this offset is the highest (and it's not a delete) */
+        val retainRecord = lastOffset < 0 || (entry.offset >= lastOffset && entry.message.payload != null)
+        if (retainRecord) {
+          ByteBufferMessageSet.writeMessage(writeBuffer, entry.message, entry.offset)
+          stats.recopyMessage(size)
+        }
+      }
+      // if any messages are to be retained, write them out
+      if(writeBuffer.position > 0) {
+        writeBuffer.flip()
+        val retained = new ByteBufferMessageSet(writeBuffer)
+        dest.append(retained.head.offset, retained)
+        throttler.maybeThrottle(writeBuffer.limit)
+      }
+      
+      // if we read bytes but didn't get even one complete message, our I/O buffer is too small, grow it and try again
+      if(readBuffer.limit > 0 && messagesRead == 0)
+        growBuffers()
+    }
+    restoreBuffers()
+  }
+  
+  /**
+   * Double the I/O buffer capacity
+   */
+  def growBuffers() {
+    if(readBuffer.capacity >= maxIoBufferSize || writeBuffer.capacity >= maxIoBufferSize)
+      throw new IllegalStateException("This log contains a message larger than maximum allowable size of %s.".format(maxIoBufferSize))
+    val newSize = math.min(this.readBuffer.capacity * 2, maxIoBufferSize)
+    info("Growing cleaner I/O buffers from " + readBuffer.capacity + "bytes to " + newSize + " bytes.")
+    this.readBuffer = ByteBuffer.allocate(newSize)
+    this.writeBuffer = ByteBuffer.allocate(newSize)
+  }
+  
+  /**
+   * Restore the I/O buffer capacity to its original size
+   */
+  def restoreBuffers() {
+    if(this.readBuffer.capacity > this.ioBufferSize)
+      this.readBuffer = ByteBuffer.allocate(this.ioBufferSize)
+    if(this.writeBuffer.capacity > this.ioBufferSize)
+      this.writeBuffer = ByteBuffer.allocate(this.ioBufferSize)
+  }
+
+  /**
+   * Group the segments in a log into groups totaling less than a given size. the size is enforced separately for the log data and the index data.
+   * We collect a group of such segments together into a single
+   * destination segment. This prevents segment sizes from shrinking too much.
+   *
+   * @param segments The log segments to group
+   * @param maxSize the maximum size in bytes for the total of all log data in a group
+   * @param maxIndexSize the maximum size in bytes for the total of all index data in a group
+   *
+   * @return A list of grouped segments
+   */
+  private[log] def groupSegmentsBySize(segments: Iterable[LogSegment], maxSize: Int, maxIndexSize: Int): List[Seq[LogSegment]] = {
+    var grouped = List[List[LogSegment]]()
+    var segs = segments.toList
+    while(!segs.isEmpty) {
+      var group = List(segs.head)
+      var logSize = segs.head.size
+      var indexSize = segs.head.index.sizeInBytes
+      segs = segs.tail
+      while(!segs.isEmpty &&
+            logSize + segs.head.size < maxSize &&
+            indexSize + segs.head.index.sizeInBytes < maxIndexSize) {
+        group = segs.head :: group
+        logSize += segs.head.size
+        indexSize += segs.head.index.sizeInBytes
+        segs = segs.tail
+      }
+      grouped ::= group.reverse
+    }
+    grouped.reverse
+  }
+
+  /**
+   * Build a map of key_hash => offset for the keys in the dirty portion of the log to use in cleaning.
+   * @param log The log to use
+   * @param start The offset at which dirty messages begin
+   * @param end The ending offset for the map that is being built
+   * @param map The map in which to store the mappings
+   *
+   * @return The final offset the map covers
+   */
+  private[log] def buildOffsetMap(log: Log, start: Long, end: Long, map: OffsetMap): Long = {
+    map.clear()
+    val segments = log.logSegments(start, end)
+    info("Building offset map for log %s for %d segments in offset range [%d, %d).".format(log.name, segments.size, start, end))
+    var offset = segments.head.baseOffset
+    require(offset == start, "Last clean offset is %d but segment base offset is %d for log %s.".format(start, offset, log.name))
+    for (segment <- segments) {
+      checkDone()
+      offset = buildOffsetMap(segment, map)
+    }
+    info("Offset map for log %s complete.".format(log.name))
+    offset
+  }
+
+  /**
+   * Add the messages in the given segment to the offset map
+   *
+   * @param segment The segment to index
+   * @param map The map in which to store the key=>offset mapping
+   *
+   * @return The final offset covered by the map
+   */
+  private def buildOffsetMap(segment: LogSegment, map: OffsetMap): Long = {
+    var position = 0
+    var offset = segment.baseOffset
+    while (position < segment.log.sizeInBytes) {
+      checkDone()
+      readBuffer.clear()
+      val messages = new ByteBufferMessageSet(segment.log.readInto(readBuffer, position))
+      throttler.maybeThrottle(messages.sizeInBytes)
+      val startPosition = position
+      for (entry <- messages) {
+        val message = entry.message
+        require(message.hasKey)
+        val size = MessageSet.entrySize(message)
+        position += size
+        map.put(message.key, entry.offset)
+        offset = entry.offset
+        stats.indexMessage(size)
+      }
+      // if we didn't read even one complete message, our read buffer may be too small
+      if(position == startPosition)
+        growBuffers()
+    }
+    restoreBuffers()
+    offset
+  }
+
+  /**
+   * If we aren't running any more throw an AllDoneException
+   */
+  private def checkDone() {
+    if (Thread.currentThread.isInterrupted)
+      throw new InterruptedException
+  }
+}
+
+/**
+ * A simple struct for collecting stats about log cleaning
+ */
+private case class CleanerStats(time: Time = SystemTime) {
+  var startTime, mapCompleteTime, endTime, bytesRead, bytesWritten, mapBytesRead, mapMessagesRead, messagesRead, messagesWritten = 0L
+  clear()
+  
+  def readMessage(size: Int) {
+    messagesRead += 1
+    bytesRead += size
+  }
+  
+  def recopyMessage(size: Int) {
+    messagesWritten += 1
+    bytesWritten += size
+  }
+  
+  def indexMessage(size: Int) {
+    mapMessagesRead += 1
+    mapBytesRead += size
+  }
+  
+  def indexDone() {
+    mapCompleteTime = time.milliseconds
+  }
+  
+  def allDone() {
+    endTime = time.milliseconds
+  }
+  
+  def elapsedSecs = (endTime - startTime)/1000.0
+  
+  def elapsedIndexSecs = (mapCompleteTime - startTime)/1000.0
+  
+  def clear() {
+    startTime = time.milliseconds
+    mapCompleteTime = -1L
+    endTime = -1L
+    bytesRead = 0L
+    bytesWritten = 0L
+    mapBytesRead = 0L
+    mapMessagesRead = 0L
+    messagesRead = 0L
+    messagesWritten = 0L
+  }
+}
+
+/**
+ * Helper class for a log, its topic/partition, and the last clean position
+ */
+private case class LogToClean(topicPartition: TopicAndPartition, log: Log, firstDirtyOffset: Long) extends Ordered[LogToClean] {
+  val cleanBytes = log.logSegments(-1, firstDirtyOffset-1).map(_.size).sum
+  val dirtyBytes = log.logSegments(firstDirtyOffset, math.max(firstDirtyOffset, log.activeSegment.baseOffset)).map(_.size).sum
+  val cleanableRatio = dirtyBytes / totalBytes.toDouble
+  def totalBytes = cleanBytes + dirtyBytes
+  override def compare(that: LogToClean): Int = math.signum(this.cleanableRatio - that.cleanableRatio).toInt
+}
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/log/LogConfig.scala b/core/src/main/scala/kafka/log/LogConfig.scala
new file mode 100644
index 00000000000..5a10bef3b36
--- /dev/null
+++ b/core/src/main/scala/kafka/log/LogConfig.scala
@@ -0,0 +1,51 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+import java.io.File
+import scala.collection._
+import kafka.common._
+
+/**
+ * Configuration settings for a log
+ * @param segmentSize The soft maximum for the size of a segment file in the log
+ * @param segmentMs The soft maximum on the amount of time before a new log segment is rolled
+ * @param flushInterval The number of messages that can be written to the log before a flush is forced
+ * @param flushMs The amount of time the log can have dirty data before a flush is forced
+ * @param retentionSize The approximate total number of bytes this log can use
+ * @param retentionMs The age approximate maximum age of the last segment that is retained
+ * @param maxIndexSize The maximum size of an index file
+ * @param indexInterval The approximate number of bytes between index entries
+ * @param fileDeleteDelayMs The time to wait before deleting a file from the filesystem
+ * @param minCleanableRatio The ratio of bytes that are available for cleaning to the bytes already cleaned
+ * @param dedupe Should old segments in this log be deleted or deduplicated?
+ */
+case class LogConfig(val segmentSize: Int = 1024*1024, 
+                     val segmentMs: Long = Long.MaxValue,
+                     val flushInterval: Long = Long.MaxValue, 
+                     val flushMs: Long = Long.MaxValue,
+                     val retentionSize: Long = Long.MaxValue,
+                     val retentionMs: Long = Long.MaxValue,
+                     val maxMessageSize: Int = Int.MaxValue,
+                     val maxIndexSize: Int = 1024*1024,
+                     val indexInterval: Int = 4096,
+                     val fileDeleteDelayMs: Long = 60*1000,
+                     val minCleanableRatio: Double = 0.5,
+                     val dedupe: Boolean = false)
+                      
+                     
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/log/LogManager.scala b/core/src/main/scala/kafka/log/LogManager.scala
index c5ab8a262b2..438d802ab23 100644
--- a/core/src/main/scala/kafka/log/LogManager.scala
+++ b/core/src/main/scala/kafka/log/LogManager.scala
@@ -36,32 +36,31 @@ import kafka.server.KafkaConfig
  * A background thread handles log retention by periodically truncating excess log segments.
  */
 @threadsafe
-class LogManager(val config: KafkaConfig,
+class LogManager(val logDirs: Array[File],
+                 val topicConfigs: Map[String, LogConfig],
+                 val defaultConfig: LogConfig,
+                 val cleanerConfig: CleanerConfig,
+                 val flushCheckMs: Long,
+                 val retentionCheckMs: Long,
                  scheduler: Scheduler,
                  private val time: Time) extends Logging {
 
   val CleanShutdownFile = ".kafka_cleanshutdown"
   val LockFile = ".lock"
   val InitialTaskDelayMs = 30*1000
-  val logDirs: Array[File] = config.logDirs.map(new File(_)).toArray
-  private val logFileSizeMap = config.logSegmentBytesPerTopicMap
-  private val logFlushInterval = config.logFlushIntervalMessages
-  private val logFlushIntervals = config.logFlushIntervalMsPerTopicMap
   private val logCreationLock = new Object
-  private val logRetentionSizeMap = config.logRetentionBytesPerTopicMap
-  private val logRetentionMsMap = config.logRetentionHoursPerTopicMap.map(e => (e._1, e._2 * 60 * 60 * 1000L)) // convert hours to ms
-  private val logRollMsMap = config.logRollHoursPerTopicMap.map(e => (e._1, e._2 * 60 * 60 * 1000L))
-  private val logRollDefaultIntervalMs = 1000L * 60 * 60 * config.logRollHours
-  private val logCleanupIntervalMs = 1000L * 60 * config.logCleanupIntervalMins
-  private val logCleanupDefaultAgeMs = 1000L * 60 * 60 * config.logRetentionHours
-
-  this.logIdent = "[Log Manager on Broker " + config.brokerId + "] "
   private val logs = new Pool[TopicAndPartition, Log]()
   
   createAndValidateLogDirs(logDirs)
   private var dirLocks = lockLogDirs(logDirs)
   loadLogs(logDirs)
   
+  private val cleaner: LogCleaner = 
+    if(cleanerConfig.enableCleaner)
+      new LogCleaner(cleanerConfig, logDirs, logs, time = time)
+    else
+      null
+  
   /**
    * Create and check validity of the given directories, specifically:
    * <ol>
@@ -114,18 +113,11 @@ class LogManager(val config: KafkaConfig,
           if(dir.isDirectory){
             info("Loading log '" + dir.getName + "'")
             val topicPartition = parseTopicPartitionName(dir.getName)
-            val rollIntervalMs = logRollMsMap.get(topicPartition.topic).getOrElse(this.logRollDefaultIntervalMs)
-            val maxLogFileSize = logFileSizeMap.get(topicPartition.topic).getOrElse(config.logSegmentBytes)
-            val log = new Log(dir,
+            val config = topicConfigs.getOrElse(topicPartition.topic, defaultConfig)
+            val log = new Log(dir, 
+                              config,
+                              needsRecovery,
                               scheduler,
-                              maxLogFileSize,
-                              config.messageMaxBytes,
-                              logFlushInterval, 
-                              rollIntervalMs, 
-                              needsRecovery, 
-                              config.logIndexSizeMaxBytes,
-                              config.logIndexIntervalBytes,
-                              config.logDeleteDelayMs,
                               time)
             val previous = this.logs.put(topicPartition, log)
             if(previous != null)
@@ -142,20 +134,41 @@ class LogManager(val config: KafkaConfig,
   def startup() {
     /* Schedule the cleanup task to delete old logs */
     if(scheduler != null) {
-      info("Starting log cleanup with a period of %d ms.".format(logCleanupIntervalMs))
-      scheduler.schedule("kafka-log-cleaner", 
+      info("Starting log cleanup with a period of %d ms.".format(retentionCheckMs))
+      scheduler.schedule("kafka-log-retention", 
                          cleanupLogs, 
                          delay = InitialTaskDelayMs, 
-                         period = logCleanupIntervalMs, 
+                         period = retentionCheckMs, 
                          TimeUnit.MILLISECONDS)
-      info("Starting log flusher with a default period of %d ms with the following overrides: %s."
-          .format(config.logFlushIntervalMs, logFlushIntervals.map(e => e._1.toString + "=" + e._2.toString).mkString(", ")))
+      info("Starting log flusher with a default period of %d ms.".format(flushCheckMs))
       scheduler.schedule("kafka-log-flusher", 
                          flushDirtyLogs, 
                          delay = InitialTaskDelayMs, 
-                         period = config.logFlushSchedulerIntervalMs,
+                         period = flushCheckMs, 
                          TimeUnit.MILLISECONDS)
     }
+    if(cleanerConfig.enableCleaner)
+      cleaner.startup()
+  }
+  
+  /**
+   * Close all the logs
+   */
+  def shutdown() {
+    debug("Shutting down.")
+    try {
+      // stop the cleaner first
+      if(cleaner != null)
+        Utils.swallow(cleaner.shutdown())
+      // close the logs
+      allLogs.foreach(_.close())
+      // mark that the shutdown was clean by creating the clean shutdown marker file
+      logDirs.foreach(dir => Utils.swallow(new File(dir, CleanShutdownFile).createNewFile()))
+    } finally {
+      // regardless of whether the close succeeded, we need to unlock the data directories
+      dirLocks.foreach(_.destroy())
+    }
+    debug("Shutdown complete.")
   }
   
   /**
@@ -197,18 +210,10 @@ class LogManager(val config: KafkaConfig,
       val dataDir = nextLogDir()
       val dir = new File(dataDir, topicAndPartition.topic + "-" + topicAndPartition.partition)
       dir.mkdirs()
-      val rollIntervalMs = logRollMsMap.get(topicAndPartition.topic).getOrElse(this.logRollDefaultIntervalMs)
-      val maxLogFileSize = logFileSizeMap.get(topicAndPartition.topic).getOrElse(config.logSegmentBytes)
       log = new Log(dir, 
+                    defaultConfig,
+                    needsRecovery = false,
                     scheduler,
-                    maxLogFileSize, 
-                    config.messageMaxBytes,
-                    logFlushInterval, 
-                    rollIntervalMs, 
-                    needsRecovery = false, 
-                    config.logIndexSizeMaxBytes,
-                    config.logIndexIntervalBytes, 
-                    config.logDeleteDelayMs,
                     time)
       info("Created log for topic %s partition %d in %s.".format(topicAndPartition.topic, topicAndPartition.partition, dataDir.getAbsolutePath))
       logs.put(topicAndPartition, log)
@@ -242,8 +247,7 @@ class LogManager(val config: KafkaConfig,
   private def cleanupExpiredSegments(log: Log): Int = {
     val startMs = time.milliseconds
     val topic = parseTopicPartitionName(log.name).topic
-    val logCleanupThresholdMs = logRetentionMsMap.get(topic).getOrElse(this.logCleanupDefaultAgeMs)
-    log.deleteOldSegments(startMs - _.lastModified > logCleanupThresholdMs)
+    log.deleteOldSegments(startMs - _.lastModified > log.config.retentionMs)
   }
 
   /**
@@ -252,10 +256,9 @@ class LogManager(val config: KafkaConfig,
    */
   private def cleanupSegmentsToMaintainSize(log: Log): Int = {
     val topic = parseTopicPartitionName(log.dir.getName).topic
-    val maxLogRetentionSize = logRetentionSizeMap.get(topic).getOrElse(config.logRetentionBytes)
-    if(maxLogRetentionSize < 0 || log.size < maxLogRetentionSize)
+    if(log.config.retentionSize < 0 || log.size < log.config.retentionSize)
       return 0
-    var diff = log.size - maxLogRetentionSize
+    var diff = log.size - log.config.retentionSize
     def shouldDelete(segment: LogSegment) = {
       if(diff - segment.size >= 0) {
         diff -= segment.size
@@ -274,7 +277,7 @@ class LogManager(val config: KafkaConfig,
     debug("Beginning log cleanup...")
     var total = 0
     val startMs = time.milliseconds
-    for(log <- allLogs) {
+    for(log <- allLogs; if !log.config.dedupe) {
       debug("Garbage collecting '" + log.name + "'")
       total += cleanupExpiredSegments(log) + cleanupSegmentsToMaintainSize(log)
     }
@@ -282,23 +285,6 @@ class LogManager(val config: KafkaConfig,
                   (time.milliseconds - startMs) / 1000 + " seconds")
   }
 
-  /**
-   * Close all the logs
-   */
-  def shutdown() {
-    debug("Shutting down.")
-    try {
-      // close the logs
-      allLogs.foreach(_.close())
-      // mark that the shutdown was clean by creating the clean shutdown marker file
-      logDirs.foreach(dir => Utils.swallow(new File(dir, CleanShutdownFile).createNewFile()))
-    } finally {
-      // regardless of whether the close succeeded, we need to unlock the data directories
-      dirLocks.foreach(_.destroy())
-    }
-    debug("Shutdown complete.")
-  }
-
   /**
    * Get all the partition logs
    */
@@ -312,13 +298,9 @@ class LogManager(val config: KafkaConfig,
     for ((topicAndPartition, log) <- logs) {
       try {
         val timeSinceLastFlush = time.milliseconds - log.lastFlushTime
-        
-        var logFlushInterval = config.logFlushIntervalMs
-        if(logFlushIntervals.contains(topicAndPartition.topic))
-          logFlushInterval = logFlushIntervals(topicAndPartition.topic)
-        debug("Checking if flush is needed on " + topicAndPartition.topic + " flush interval  " + logFlushInterval +
+        debug("Checking if flush is needed on " + topicAndPartition.topic + " flush interval  " + log.config.flushMs +
               " last flushed " + log.lastFlushTime + " time since last flush: " + timeSinceLastFlush)
-        if(timeSinceLastFlush >= logFlushInterval)
+        if(timeSinceLastFlush >= log.config.flushMs)
           log.flush
       } catch {
         case e =>
diff --git a/core/src/main/scala/kafka/log/LogSegment.scala b/core/src/main/scala/kafka/log/LogSegment.scala
index 39dd9c203ce..120ebeb7f37 100644
--- a/core/src/main/scala/kafka/log/LogSegment.scala
+++ b/core/src/main/scala/kafka/log/LogSegment.scala
@@ -79,7 +79,7 @@ class LogSegment(val log: FileMessageSet,
    * @return The position in the log storing the message with the least offset >= the requested offset or null if no message meets this criteria.
    */
   @threadsafe
-  private def translateOffset(offset: Long, startingFilePosition: Int = 0): OffsetPosition = {
+  private[log] def translateOffset(offset: Long, startingFilePosition: Int = 0): OffsetPosition = {
     val mapping = index.lookup(offset)
     log.searchFor(offset, max(mapping.position, startingFilePosition))
   }
@@ -168,18 +168,20 @@ class LogSegment(val log: FileMessageSet,
    * Truncate off all index and log entries with offsets >= the given offset.
    * If the given offset is larger than the largest message in this segment, do nothing.
    * @param offset The offset to truncate to
+   * @return The number of log bytes truncated
    */
   @nonthreadsafe
-  def truncateTo(offset: Long) {
+  def truncateTo(offset: Long): Int = {
     val mapping = translateOffset(offset)
     if(mapping == null)
-      return
+      return 0
     index.truncateTo(offset)
     // after truncation, reset and allocate more space for the (new currently  active) index
     index.resize(index.maxIndexSize)
-    log.truncateTo(mapping.position)
-    if (log.sizeInBytes == 0)
+    val bytesTruncated = log.truncateTo(mapping.position)
+    if(log.sizeInBytes == 0)
       created = time.milliseconds
+    bytesTruncated
   }
   
   /**
@@ -210,6 +212,18 @@ class LogSegment(val log: FileMessageSet,
     }
   }
   
+  /**
+   * Change the suffix for the index and log file for this log segment
+   */
+  def changeFileSuffixes(oldSuffix: String, newSuffix: String) {
+    val logRenamed = log.renameTo(new File(Utils.replaceSuffix(log.file.getPath, oldSuffix, newSuffix)))
+    if(!logRenamed)
+      throw new KafkaStorageException("Failed to change the log file suffix from %s to %s for log segment %d".format(oldSuffix, newSuffix, baseOffset))
+    val indexRenamed = index.renameTo(new File(Utils.replaceSuffix(index.file.getPath, oldSuffix, newSuffix)))
+    if(!indexRenamed)
+      throw new KafkaStorageException("Failed to change the index file suffix from %s to %s for log segment %d".format(oldSuffix, newSuffix, baseOffset))
+  }
+  
   /**
    * Close this log segment
    */
diff --git a/core/src/main/scala/kafka/log/OffsetIndex.scala b/core/src/main/scala/kafka/log/OffsetIndex.scala
index 1662f107b4d..23e659f742f 100644
--- a/core/src/main/scala/kafka/log/OffsetIndex.scala
+++ b/core/src/main/scala/kafka/log/OffsetIndex.scala
@@ -49,7 +49,7 @@ import kafka.utils._
  * All external APIs translate from relative offsets to full offsets, so users of this class do not interact with the internal 
  * storage format.
  */
-class OffsetIndex(val file: File, val baseOffset: Long, val maxIndexSize: Int = -1) extends Logging {
+class OffsetIndex(@volatile var file: File, val baseOffset: Long, val maxIndexSize: Int = -1) extends Logging {
   
   /* initialize the memory mapping for this index */
   private var mmap: MappedByteBuffer = 
@@ -83,20 +83,15 @@ class OffsetIndex(val file: File, val baseOffset: Long, val maxIndexSize: Int =
         Utils.swallow(raf.close())
       }
     }
-
-  info("Created index file %s with maxEntries = %d, maxIndexSize = %d, entries = %d, lastOffset = %d"
-    .format(file.getAbsolutePath, maxEntries, maxIndexSize, entries(), lastOffset))
-
-  /**
-   * The maximum number of eight-byte entries this index can hold
-   */
-  def maxEntries = mmap.limit / 8
   
   /* the number of eight-byte entries currently in the index */
   private var size = new AtomicInteger(mmap.position / 8)
   
   /* the last offset in the index */
   var lastOffset = readLastOffset()
+  
+  info("Created index file %s with maxEntries = %d, maxIndexSize = %d, entries = %d, lastOffset = %d"
+       .format(file.getAbsolutePath, maxEntries, maxIndexSize, entries(), lastOffset))
 
   /**
    * The last offset written to the index
@@ -109,6 +104,11 @@ class OffsetIndex(val file: File, val baseOffset: Long, val maxIndexSize: Int =
       }
     baseOffset + offset
   }
+  
+  /**
+   * The maximum number of eight-byte entries this index can hold
+   */
+  def maxEntries = mmap.limit / 8
 
   /**
    * Find the largest offset less than or equal to the given targetOffset 
@@ -284,11 +284,26 @@ class OffsetIndex(val file: File, val baseOffset: Long, val maxIndexSize: Int =
   /** The number of entries in this index */
   def entries() = size.get
   
+  /**
+   * The number of bytes actually used by this index
+   */
+  def sizeInBytes() = 8 * entries
+  
   /** Close the index */
   def close() {
     trimToValidSize()
   }
   
+  /**
+   * Rename the file that backs this offset index
+   * @return true iff the rename was successful
+   */
+  def renameTo(f: File): Boolean = {
+    val success = this.file.renameTo(f)
+    this.file = f
+    success
+  }
+  
   /**
    * Round a number to the greatest exact multiple of the given factor less than the given number.
    * E.g. roundToExactMultiple(67, 8) == 64
diff --git a/core/src/main/scala/kafka/log/OffsetMap.scala b/core/src/main/scala/kafka/log/OffsetMap.scala
new file mode 100644
index 00000000000..623681361e4
--- /dev/null
+++ b/core/src/main/scala/kafka/log/OffsetMap.scala
@@ -0,0 +1,136 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+import java.util.Arrays
+import java.security.MessageDigest
+import java.nio.ByteBuffer
+import kafka.utils._
+
+trait OffsetMap {
+  def capacity: Int
+  def put(key: ByteBuffer, offset: Long)
+  def get(key: ByteBuffer): Long
+  def clear()
+  def size: Int
+  def utilization: Double = size.toDouble / capacity
+}
+
+/**
+ * An approximate map used for deduplicating the log.
+ * @param memory The amount of memory this map can use
+ * @param maxLoadFactor The maximum percent full this offset map can be
+ * @param hashAlgorithm The hash algorithm instance to use: MD2, MD5, SHA-1, SHA-256, SHA-384, SHA-512
+ */
+@nonthreadsafe
+class SkimpyOffsetMap(val memory: Int, val maxLoadFactor: Double, val hashAlgorithm: String = "MD5") extends OffsetMap {
+  private val bytes = ByteBuffer.allocate(memory)
+  
+  /* the hash algorithm instance to use, defualt is MD5 */
+  private val digest = MessageDigest.getInstance(hashAlgorithm)
+  
+  /* the number of bytes for this hash algorithm */
+  private val hashSize = digest.getDigestLength
+  
+  /* create some hash buffers to avoid reallocating each time */
+  private val hash1 = new Array[Byte](hashSize)
+  private val hash2 = new Array[Byte](hashSize)
+  
+  /* number of entries put into the map */
+  private var entries = 0
+  
+  /* a byte added as a prefix to all keys to make collisions non-static in repeated uses. Changed in clear(). */
+  private var salt: Byte = 0
+  
+  /**
+   * The number of bytes of space each entry uses (the number of bytes in the hash plus an 8 byte offset)
+   */
+  val bytesPerEntry = hashSize + 8
+  
+  /**
+   * The maximum number of entries this map can contain before it exceeds the max load factor
+   */
+  override val capacity: Int = (maxLoadFactor * memory / bytesPerEntry).toInt
+  
+  /**
+   * Associate a offset with a key.
+   * @param key The key
+   * @param offset The offset
+   */
+  override def put(key: ByteBuffer, offset: Long) {
+    if(size + 1 > capacity)
+      throw new IllegalStateException("Attempt to add to a full offset map with a maximum capacity of %d.".format(capacity))
+    hash(key, hash1)
+    bytes.position(offsetFor(hash1))
+    bytes.put(hash1)
+    bytes.putLong(offset)
+    entries += 1
+  }
+  
+  /**
+   * Get the offset associated with this key. This method is approximate,
+   * it may not find an offset previously stored, but cannot give a wrong offset.
+   * @param key The key
+   * @return The offset associated with this key or -1 if the key is not found
+   */
+  override def get(key: ByteBuffer): Long = {
+    hash(key, hash1)
+    bytes.position(offsetFor(hash1))
+    bytes.get(hash2)
+    // if the computed hash equals the stored hash return the stored offset
+    if(Arrays.equals(hash1, hash2))
+      bytes.getLong()
+    else
+      -1L
+  }
+  
+  /**
+   * Change the salt used for key hashing making all existing keys unfindable.
+   * Doesn't actually zero out the array.
+   */
+  override def clear() {
+    this.entries = 0
+    this.salt = (this.salt + 1).toByte
+    Arrays.fill(bytes.array, bytes.arrayOffset, bytes.arrayOffset + bytes.limit, 0.toByte)
+  }
+  
+  /**
+   * The number of entries put into the map (note that not all may remain)
+   */
+  override def size: Int = entries
+  
+  /**
+   * Choose a slot in the array for this hash
+   */
+  private def offsetFor(hash: Array[Byte]): Int = 
+    bytesPerEntry * (Utils.abs(Utils.readInt(hash, 0)) % capacity)
+  
+  /**
+   * The offset at which we have stored the given key
+   * @param key The key to hash
+   * @param buffer The buffer to store the hash into
+   */
+  private def hash(key: ByteBuffer, buffer: Array[Byte]) {
+    key.mark()
+    digest.update(salt)
+    digest.update(key)
+    key.reset()
+    digest.digest(buffer, 0, hashSize)
+  }
+  
+}
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/message/ByteBufferMessageSet.scala b/core/src/main/scala/kafka/message/ByteBufferMessageSet.scala
index 873699ff7e2..1b9c8f89ea4 100644
--- a/core/src/main/scala/kafka/message/ByteBufferMessageSet.scala
+++ b/core/src/main/scala/kafka/message/ByteBufferMessageSet.scala
@@ -73,7 +73,7 @@ object ByteBufferMessageSet {
     new ByteBufferMessageSet(outputBuffer)
   }
     
-  private def writeMessage(buffer: ByteBuffer, message: Message, offset: Long) {
+  private[kafka] def writeMessage(buffer: ByteBuffer, message: Message, offset: Long) {
     buffer.putLong(offset)
     buffer.putInt(message.size)
     buffer.put(message.buffer)
@@ -150,7 +150,7 @@ class ByteBufferMessageSet(@BeanProperty val buffer: ByteBuffer) extends Message
           return allDone()
         val offset = topIter.getLong()
         val size = topIter.getInt()
-        if(size < 0)
+        if(size < 0 || size < Message.MinHeaderSize)
           throw new InvalidMessageException("Message found with corrupt size (" + size + ")")
         
         // we have an incomplete message
diff --git a/core/src/main/scala/kafka/server/HighwaterMarkCheckpoint.scala b/core/src/main/scala/kafka/server/HighwaterMarkCheckpoint.scala
deleted file mode 100644
index 5aa01414c8c..00000000000
--- a/core/src/main/scala/kafka/server/HighwaterMarkCheckpoint.scala
+++ /dev/null
@@ -1,118 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package kafka.server
-
-import kafka.utils.Logging
-import kafka.common._
-import java.util.concurrent.locks.ReentrantLock
-import java.io._
-
-/**
- * This class handles the read/write to the highwaterMark checkpoint file. The file stores the high watermark value for
- * all topics and partitions that this broker hosts. The format of this file is as follows -
- * version
- * number of entries
- * topic partition highwatermark
- */
-
-object HighwaterMarkCheckpoint {
-  val highWatermarkFileName = "replication-offset-checkpoint"
-  val currentHighwaterMarkFileVersion = 0
-}
-
-class HighwaterMarkCheckpoint(val path: String) extends Logging {
-  /* create the highwatermark file handle for all partitions */
-  val name = path + "/" + HighwaterMarkCheckpoint.highWatermarkFileName
-  private val hwFile = new File(name)
-  private val hwFileLock = new ReentrantLock()
-  // recover from previous tmp file, if required
-
-  def write(highwaterMarksPerPartition: Map[TopicAndPartition, Long]) {
-    hwFileLock.lock()
-    try {
-      // write to temp file and then swap with the highwatermark file
-      val tempHwFile = new File(hwFile + ".tmp")
-
-      val hwFileWriter = new BufferedWriter(new FileWriter(tempHwFile))
-      // checkpoint highwatermark for all partitions
-      // write the current version
-      hwFileWriter.write(HighwaterMarkCheckpoint.currentHighwaterMarkFileVersion.toString)
-      hwFileWriter.newLine()
-      // write the number of entries in the highwatermark file
-      hwFileWriter.write(highwaterMarksPerPartition.size.toString)
-      hwFileWriter.newLine()
-
-      highwaterMarksPerPartition.foreach { partitionAndHw =>
-        hwFileWriter.write("%s %s %s".format(partitionAndHw._1.topic, partitionAndHw._1.partition, partitionAndHw._2))
-        hwFileWriter.newLine()
-      }
-      hwFileWriter.flush()
-      hwFileWriter.close()
-      // swap new high watermark file with previous one
-      if(!tempHwFile.renameTo(hwFile)) {
-        fatal("Attempt to swap the new high watermark file with the old one failed")
-        System.exit(1)
-      }
-    }finally {
-      hwFileLock.unlock()
-    }
-  }
-
-  def read(topic: String, partition: Int): Long = {
-    hwFileLock.lock()
-    try {
-      hwFile.length() match {
-        case 0 => 
-          warn("No highwatermark file is found. Returning 0 as the highwatermark for topic %s partition %d."
-            .format(topic, partition))
-          0L
-        case _ =>
-          val hwFileReader = new BufferedReader(new FileReader(hwFile))
-          val version = hwFileReader.readLine().toShort
-          version match {
-            case HighwaterMarkCheckpoint.currentHighwaterMarkFileVersion =>
-              val numberOfHighWatermarks = hwFileReader.readLine().toInt
-              val partitionHighWatermarks =
-                for(i <- 0 until numberOfHighWatermarks) yield {
-                  val nextHwEntry = hwFileReader.readLine()
-                  val partitionHwInfo = nextHwEntry.split(" ")
-                  val topic = partitionHwInfo(0)
-                  val partitionId = partitionHwInfo(1).toInt
-                  val highWatermark = partitionHwInfo(2).toLong
-                  (TopicAndPartition(topic, partitionId) -> highWatermark)
-                }
-              hwFileReader.close()
-              val hwOpt = partitionHighWatermarks.toMap.get(TopicAndPartition(topic, partition))
-              hwOpt match {
-                case Some(hw) => 
-                  debug("Read hw %d for topic %s partition %d from highwatermark checkpoint file".format(hw, topic, partition))
-                  hw
-                case None => 
-                  warn("No previously checkpointed highwatermark value found for topic %s ".format(topic) +
-                       "partition %d. Returning 0 as the highwatermark".format(partition))
-                  0L
-              }
-            case _ => fatal("Unrecognized version of the highwatermark checkpoint file " + version)
-            System.exit(1)
-            -1L
-          }
-      }
-    }finally {
-      hwFileLock.unlock()
-    }
-  }
-}
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/server/KafkaConfig.scala b/core/src/main/scala/kafka/server/KafkaConfig.scala
index 51ea727ee77..f4ba59cfde6 100644
--- a/core/src/main/scala/kafka/server/KafkaConfig.scala
+++ b/core/src/main/scala/kafka/server/KafkaConfig.scala
@@ -103,9 +103,37 @@ class KafkaConfig private (val props: VerifiableProperties) extends ZKConfig(pro
 
   /* the maximum size of the log for some specific topic before deleting it */
   val logRetentionBytesPerTopicMap = props.getMap("log.retention.bytes.per.topic", _.toLong > 0).mapValues(_.toLong)
-
+  
   /* the frequency in minutes that the log cleaner checks whether any log is eligible for deletion */
-  val logCleanupIntervalMins = props.getIntInRange("log.cleanup.interval.mins", 10, (1, Int.MaxValue))
+  val logCleanupIntervalMs = props.getLongInRange("log.retention.check.interval.ms", 5*60*1000, (1, Long.MaxValue))
+  
+  /* the default cleanup policy for segments beyond the retention window, must be either "delete" or "dedupe" */
+  val logCleanupPolicy = props.getString("log.cleanup.policy", "delete")
+  
+  /* a per-topic override for the cleanup policy for segments beyond the retention window */
+  val logCleanupPolicyMap = props.getMap("topic.log.cleanup.policy")
+  
+  /* the number of background threads to use for log cleaning */
+  val logCleanerThreads = props.getIntInRange("log.cleaner.threads", 1, (0, Int.MaxValue))
+  
+  /* the log cleaner will be throttled so that the sum of its read and write i/o will be less than this value on average */
+  val logCleanerIoMaxBytesPerSecond = props.getDouble("log.cleaner.io.max.bytes.per.second", Double.MaxValue)
+  
+  /* the total memory used for log deduplication across all cleaner threads */
+  val logCleanerDedupeBufferSize = props.getIntInRange("log.cleaner.dedupe.buffer.size", 500*1024*1024, (0, Int.MaxValue))
+  require(logCleanerDedupeBufferSize / logCleanerThreads > 1024*1024, "log.cleaner.dedupe.buffer.size must be at least 1MB per cleaner thread.")
+  
+  /* the total memory used for log cleaner I/O buffers across all cleaner threads */
+  val logCleanerIoBufferSize = props.getIntInRange("log.cleaner.io.buffer.size", 4*1024*1024, (0, Int.MaxValue))
+  
+  /* the amount of time to sleep when there are no logs to clean */
+  val logCleanerBackoffMs = props.getLongInRange("log.cleaner.backoff.ms", 30*1000, (0L, Long.MaxValue))
+  
+  /* the minimum ratio of dirty log to total log for a log to eligible for cleaning */
+  val logCleanerMinCleanRatio = props.getDouble("log.cleaner.min.cleanable.ratio", 0.5)
+  
+  /* should we enable log cleaning? */
+  val logCleanerEnable = props.getBoolean("log.cleaner.enable", false)
   
   /* the maximum size in bytes of the offset index */
   val logIndexSizeMaxBytes = props.getIntInRange("log.index.size.max.bytes", 10*1024*1024, (4, Int.MaxValue))
@@ -116,6 +144,7 @@ class KafkaConfig private (val props: VerifiableProperties) extends ZKConfig(pro
   /* the number of messages accumulated on a log partition before messages are flushed to disk */
   val logFlushIntervalMessages = props.getIntInRange("log.flush.interval.messages", 500, (1, Int.MaxValue))
 
+  /* the amount of time to wait before deleting a file from the filesystem */
   val logDeleteDelayMs = props.getLongInRange("log.segment.delete.delay.ms", 60000, (0, Long.MaxValue))
 
   /* the maximum time in ms that a message in selected topics is kept in memory before flushed to disk, e.g., topic1:3000,topic2: 6000  */
diff --git a/core/src/main/scala/kafka/server/KafkaServer.scala b/core/src/main/scala/kafka/server/KafkaServer.scala
index 9258b133c0a..da6f716676e 100644
--- a/core/src/main/scala/kafka/server/KafkaServer.scala
+++ b/core/src/main/scala/kafka/server/KafkaServer.scala
@@ -18,9 +18,12 @@
 package kafka.server
 
 import kafka.network.SocketServer
+import kafka.log.LogConfig
+import kafka.log.CleanerConfig
 import kafka.log.LogManager
 import kafka.utils._
 import java.util.concurrent._
+import java.io.File
 import atomic.AtomicBoolean
 import org.I0Itec.zkclient.ZkClient
 import kafka.controller.{ControllerStats, KafkaController}
@@ -56,9 +59,7 @@ class KafkaServer(val config: KafkaConfig, time: Time = SystemTime) extends Logg
     kafkaScheduler.startup()
 
     /* start log manager */
-    logManager = new LogManager(config,
-                                kafkaScheduler,
-                                time)
+    logManager = createLogManager(config)
     logManager.startup()
 
     socketServer = new SocketServer(config.brokerId,
@@ -138,6 +139,50 @@ class KafkaServer(val config: KafkaConfig, time: Time = SystemTime) extends Logg
   def awaitShutdown(): Unit = shutdownLatch.await()
 
   def getLogManager(): LogManager = logManager
+  
+  private def createLogManager(config: KafkaConfig): LogManager = {
+    val topics = config.logCleanupPolicyMap.keys ++ 
+                 config.logSegmentBytesPerTopicMap.keys ++ 
+                 config.logFlushIntervalMsPerTopicMap.keys ++ 
+                 config.logRollHoursPerTopicMap.keys ++ 
+                 config.logRetentionBytesPerTopicMap.keys ++ 
+                 config.logRetentionHoursPerTopicMap.keys
+    val defaultLogConfig = LogConfig(segmentSize = config.logSegmentBytes, 
+                                     segmentMs = 60 * 60 * 1000 * config.logRollHours,
+                                     flushInterval = config.logFlushIntervalMessages,
+                                     flushMs = config.logFlushIntervalMs.toLong,
+                                     retentionSize = config.logRetentionBytes,
+                                     retentionMs = 60 * 60 * 1000 * config.logRetentionHours,
+                                     maxMessageSize = config.messageMaxBytes,
+                                     maxIndexSize = config.logIndexSizeMaxBytes,
+                                     indexInterval = config.logIndexIntervalBytes,
+                                     fileDeleteDelayMs = config.logDeleteDelayMs,
+                                     minCleanableRatio = config.logCleanerMinCleanRatio,
+                                     dedupe = config.logCleanupPolicy.trim.toLowerCase == "dedupe")
+    val logConfigs = for(topic <- topics) yield 
+      topic -> defaultLogConfig.copy(segmentSize = config.logSegmentBytesPerTopicMap.getOrElse(topic, config.logSegmentBytes), 
+                                     segmentMs = 60 * 60 * 1000 * config.logRollHoursPerTopicMap.getOrElse(topic, config.logRollHours),
+                                     flushMs = config.logFlushIntervalMsPerTopicMap.getOrElse(topic, config.logFlushIntervalMs).toLong,
+                                     retentionSize = config.logRetentionBytesPerTopicMap.getOrElse(topic, config.logRetentionBytes),
+                                     retentionMs = 60 * 60 * 1000 * config.logRetentionHoursPerTopicMap.getOrElse(topic, config.logRetentionHours),
+                                     dedupe = config.logCleanupPolicyMap.getOrElse(topic, config.logCleanupPolicy).trim.toLowerCase == "dedupe")
+    val cleanerConfig = CleanerConfig(numThreads = config.logCleanerThreads,
+                                      dedupeBufferSize = config.logCleanerDedupeBufferSize,
+                                      ioBufferSize = config.logCleanerIoBufferSize,
+                                      maxMessageSize = config.messageMaxBytes,
+                                      maxIoBytesPerSecond = config.logCleanerIoMaxBytesPerSecond,
+                                      backOffMs = config.logCleanerBackoffMs,
+                                      enableCleaner = config.logCleanerEnable)
+    new LogManager(logDirs = config.logDirs.map(new File(_)).toArray,
+                   topicConfigs = logConfigs.toMap,
+                   defaultConfig = defaultLogConfig,
+                   cleanerConfig = cleanerConfig,
+                   flushCheckMs = config.logFlushSchedulerIntervalMs,
+                   retentionCheckMs = config.logCleanupIntervalMs,
+                   scheduler = kafkaScheduler,
+                   time = time)
+  }
+
 }
 
 
diff --git a/core/src/main/scala/kafka/server/OffsetCheckpoint.scala b/core/src/main/scala/kafka/server/OffsetCheckpoint.scala
new file mode 100644
index 00000000000..79f29df770d
--- /dev/null
+++ b/core/src/main/scala/kafka/server/OffsetCheckpoint.scala
@@ -0,0 +1,103 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package kafka.server
+
+import scala.collection._
+import kafka.utils.Logging
+import kafka.common._
+import java.util.concurrent.locks.ReentrantLock
+import java.io._
+
+/**
+ * This class saves out a map of topic/partition=>offsets to a file
+ */
+class OffsetCheckpoint(val file: File) extends Logging {
+  private val lock = new Object()
+  new File(file + ".tmp").delete() // try to delete any existing temp files for cleanliness
+  file.createNewFile() // in case the file doesn't exist
+
+  def write(offsets: Map[TopicAndPartition, Long]) {
+    lock synchronized {
+      // write to temp file and then swap with the existing file
+      val temp = new File(file.getAbsolutePath + ".tmp")
+
+      val writer = new BufferedWriter(new FileWriter(temp))
+      try {
+        // write the current version
+        writer.write(0.toString)
+        writer.newLine()
+      
+        // write the number of entries
+        writer.write(offsets.size.toString)
+        writer.newLine()
+
+        // write the entries
+        offsets.foreach { case (topicPart, offset) =>
+          writer.write("%s %d %d".format(topicPart.topic, topicPart.partition, offset))
+          writer.newLine()
+        }
+      
+        // flush and overwrite old file
+        writer.flush()
+        if(!temp.renameTo(file))
+          throw new IOException("File rename from %s to %s failed.".format(temp.getAbsolutePath, file.getAbsolutePath))
+      } finally {
+        writer.close()
+      }
+    }
+  }
+
+  def read(): Map[TopicAndPartition, Long] = {
+    lock synchronized {
+      val reader = new BufferedReader(new FileReader(file))
+      try {
+        var line = reader.readLine()
+        if(line == null)
+          return Map.empty
+        val version = line.toInt
+        version match {
+          case 0 =>
+            line = reader.readLine()
+            if(line == null)
+              return Map.empty
+            val expectedSize = line.toInt
+            var offsets = Map[TopicAndPartition, Long]()
+            line = reader.readLine()
+            while(line != null) {
+              val pieces = line.split("\\s+")
+              if(pieces.length != 3)
+                throw new IOException("Malformed line in offset checkpoint file: '%s'.".format(line))
+              
+              val topic = pieces(0)
+              val partition = pieces(1).toInt
+              val offset = pieces(2).toLong
+              offsets += (TopicAndPartition(pieces(0), partition) -> offset)
+              line = reader.readLine()
+            }
+            if(offsets.size != expectedSize)
+              throw new IOException("Expected %d entries but found only %d".format(expectedSize, offsets.size))
+            offsets
+          case _ => 
+            throw new IOException("Unrecognized version of the highwatermark checkpoint file: " + version)
+        }
+      } finally {
+        reader.close()
+      }
+    }
+  }
+  
+}
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/server/ReplicaManager.scala b/core/src/main/scala/kafka/server/ReplicaManager.scala
index 7810c214c74..710c08b0134 100644
--- a/core/src/main/scala/kafka/server/ReplicaManager.scala
+++ b/core/src/main/scala/kafka/server/ReplicaManager.scala
@@ -20,6 +20,7 @@ import kafka.cluster.{Broker, Partition, Replica}
 import collection._
 import mutable.HashMap
 import org.I0Itec.zkclient.ZkClient
+import java.io.{File, IOException}
 import java.util.concurrent.atomic.AtomicBoolean
 import kafka.utils._
 import kafka.log.LogManager
@@ -33,6 +34,7 @@ import kafka.controller.KafkaController
 
 object ReplicaManager {
   val UnknownLogEndOffset = -1L
+  val HighWatermarkFilename = "replication-offset-checkpoint"
 }
 
 class ReplicaManager(val config: KafkaConfig, 
@@ -48,7 +50,7 @@ class ReplicaManager(val config: KafkaConfig,
   val replicaFetcherManager = new ReplicaFetcherManager(config, this)
   this.logIdent = "Replica Manager on Broker " + config.brokerId + ": "
   private val highWatermarkCheckPointThreadStarted = new AtomicBoolean(false)
-  val highWatermarkCheckpoints = config.logDirs.map(dir => (dir, new HighwaterMarkCheckpoint(dir))).toMap
+  val highWatermarkCheckpoints = config.logDirs.map(dir => (dir, new OffsetCheckpoint(new File(dir, ReplicaManager.HighWatermarkFilename)))).toMap
 
   newGauge(
     "LeaderCount",
@@ -67,7 +69,7 @@ class ReplicaManager(val config: KafkaConfig,
     }
   )
   val isrExpandRate = newMeter("IsrExpandsPerSec",  "expands", TimeUnit.SECONDS)
-  val isrShrinkRate = newMeter("ISRShrinksPerSec",  "shrinks", TimeUnit.SECONDS)
+  val isrShrinkRate = newMeter("IsrShrinksPerSec",  "shrinks", TimeUnit.SECONDS)
 
 
   def startHighWaterMarksCheckPointThread() = {
@@ -265,7 +267,13 @@ class ReplicaManager(val config: KafkaConfig,
     val replicasByDir = replicas.filter(_.log.isDefined).groupBy(_.log.get.dir.getParent)
     for((dir, reps) <- replicasByDir) {
       val hwms = reps.map(r => (TopicAndPartition(r.topic, r.partitionId) -> r.highWatermark)).toMap
-      highWatermarkCheckpoints(dir).write(hwms)
+      try {
+        highWatermarkCheckpoints(dir).write(hwms)
+      } catch {
+        case e: IOException =>
+          fatal("Error writing to highwatermark file: ", e)
+          Runtime.getRuntime().halt(1)
+      }
     }
   }
 
diff --git a/core/src/main/scala/kafka/utils/FileLock.scala b/core/src/main/scala/kafka/utils/FileLock.scala
index ad7a59742b8..a5761b9db31 100644
--- a/core/src/main/scala/kafka/utils/FileLock.scala
+++ b/core/src/main/scala/kafka/utils/FileLock.scala
@@ -9,56 +9,56 @@ import java.nio.channels._
  * The given path will be created and opened if it doesn't exist.
  */
 class FileLock(val file: File) extends Logging {
-    file.createNewFile()
-    private val channel = new RandomAccessFile(file, "rw").getChannel()
-    private var flock: java.nio.channels.FileLock = null
-    
-    /**
-     * Lock the file or throw an exception if the lock is already held
-     */
-    def lock() {
-      this synchronized {
-        trace("Acquiring lock on " + file.getAbsolutePath)
-        flock = channel.lock()
-      }
+  file.createNewFile() // create the file if it doesn't exist
+  private val channel = new RandomAccessFile(file, "rw").getChannel()
+  private var flock: java.nio.channels.FileLock = null
+
+  /**
+   * Lock the file or throw an exception if the lock is already held
+   */
+  def lock() {
+    this synchronized {
+      trace("Acquiring lock on " + file.getAbsolutePath)
+      flock = channel.lock()
     }
-    
-    /**
-     * Try to lock the file and return true if the locking succeeds
-     */
-    def tryLock(): Boolean = {
-      this synchronized {
-        trace("Acquiring lock on " + file.getAbsolutePath)
-        try {
-          // weirdly this method will return null if the lock is held by another
-          // process, but will throw an exception if the lock is held by this process
-          // so we have to handle both cases
-          flock = channel.tryLock()
-          flock != null
-        } catch {
-          case e: OverlappingFileLockException => false
-        }
+  }
+
+  /**
+   * Try to lock the file and return true if the locking succeeds
+   */
+  def tryLock(): Boolean = {
+    this synchronized {
+      trace("Acquiring lock on " + file.getAbsolutePath)
+      try {
+        // weirdly this method will return null if the lock is held by another
+        // process, but will throw an exception if the lock is held by this process
+        // so we have to handle both cases
+        flock = channel.tryLock()
+        flock != null
+      } catch {
+        case e: OverlappingFileLockException => false
       }
     }
-    
-    /**
-     * Unlock the lock if it is held
-     */
-    def unlock() {
-      this synchronized {
-        trace("Releasing lock on " + file.getAbsolutePath)
-        if(flock != null)
-          flock.release()
-      }
+  }
+
+  /**
+   * Unlock the lock if it is held
+   */
+  def unlock() {
+    this synchronized {
+      trace("Releasing lock on " + file.getAbsolutePath)
+      if(flock != null)
+        flock.release()
     }
-    
-    /**
-     * Destroy this lock, closing the associated FileChannel
-     */
-    def destroy() = {
-      this synchronized {
-        unlock()
-        channel.close()
-      }
+  }
+
+  /**
+   * Destroy this lock, closing the associated FileChannel
+   */
+  def destroy() = {
+    this synchronized {
+      unlock()
+      channel.close()
     }
+  }
 }
\ No newline at end of file
diff --git a/core/src/main/scala/kafka/utils/Logging.scala b/core/src/main/scala/kafka/utils/Logging.scala
index d9f010bfe7a..2890e7f51dd 100644
--- a/core/src/main/scala/kafka/utils/Logging.scala
+++ b/core/src/main/scala/kafka/utils/Logging.scala
@@ -23,12 +23,13 @@ trait Logging {
   val loggerName = this.getClass.getName
   lazy val logger = Logger.getLogger(loggerName)
 
-  protected var logIdent = ""
+  protected var logIdent: String = null
 
   // Force initialization to register Log4jControllerMBean
   private val log4jController = Log4jController
 
-  private def msgWithLogIdent(msg: String) = logIdent + msg
+  private def msgWithLogIdent(msg: String) = 
+    if(logIdent == null) msg else logIdent + msg
 
   def trace(msg: => String): Unit = {
     if (logger.isTraceEnabled())
diff --git a/core/src/main/scala/kafka/utils/Throttler.scala b/core/src/main/scala/kafka/utils/Throttler.scala
index 9e53b03c612..c6c3c75ee84 100644
--- a/core/src/main/scala/kafka/utils/Throttler.scala
+++ b/core/src/main/scala/kafka/utils/Throttler.scala
@@ -32,20 +32,14 @@ import scala.math._
  */
 @threadsafe
 class Throttler(val desiredRatePerSec: Double, 
-                val checkIntervalMs: Long, 
-                val throttleDown: Boolean, 
-                val time: Time) extends Logging {
+                val checkIntervalMs: Long = 100L, 
+                val throttleDown: Boolean = true, 
+                val time: Time = SystemTime) extends Logging {
   
   private val lock = new Object
   private var periodStartNs: Long = time.nanoseconds
   private var observedSoFar: Double = 0.0
   
-  def this(desiredRatePerSec: Double, throttleDown: Boolean) = 
-    this(desiredRatePerSec, Throttler.DefaultCheckIntervalMs, throttleDown, SystemTime)
-
-  def this(desiredRatePerSec: Double) = 
-    this(desiredRatePerSec, Throttler.DefaultCheckIntervalMs, true, SystemTime)
-  
   def maybeThrottle(observed: Double) {
     lock synchronized {
       observedSoFar += observed
@@ -58,11 +52,11 @@ class Throttler(val desiredRatePerSec: Double,
         val needAdjustment = !(throttleDown ^ (rateInSecs > desiredRatePerSec))
         if(needAdjustment) {
           // solve for the amount of time to sleep to make us hit the desired rate
-          val desiredRateMs = desiredRatePerSec / Time.MsPerSec.asInstanceOf[Double]
+          val desiredRateMs = desiredRatePerSec / Time.MsPerSec.toDouble
           val elapsedMs = elapsedNs / Time.NsPerMs
           val sleepTime = round(observedSoFar / desiredRateMs - elapsedMs)
           if(sleepTime > 0) {
-            println("Natural rate is %f per second but desired rate is %f, sleeping for %d ms to compensate.".format(rateInSecs, desiredRatePerSec, sleepTime))
+            trace("Natural rate is %f per second but desired rate is %f, sleeping for %d ms to compensate.".format(rateInSecs, desiredRatePerSec, sleepTime))
             time.sleep(sleepTime)
           }
         }
@@ -76,20 +70,20 @@ class Throttler(val desiredRatePerSec: Double,
 
 object Throttler {
   
-  val DefaultCheckIntervalMs = 100L
-  
   def main(args: Array[String]) {
     val rand = new Random()
-    val throttler = new Throttler(1000000, 100, true, SystemTime)
+    val throttler = new Throttler(100000, 100, true, SystemTime)
+    val interval = 30000
     var start = System.currentTimeMillis
     var total = 0
     while(true) {
       val value = rand.nextInt(1000)
+      Thread.sleep(1)
       throttler.maybeThrottle(value)
       total += value
       val now = System.currentTimeMillis
-      if(now - start >= 1000) {
-        println(total)
+      if(now - start >= interval) {
+        println(total / (interval/1000.0))
         start = now
         total = 0
       }
diff --git a/core/src/main/scala/kafka/utils/Utils.scala b/core/src/main/scala/kafka/utils/Utils.scala
index 2a01f696f93..1c882269df7 100644
--- a/core/src/main/scala/kafka/utils/Utils.scala
+++ b/core/src/main/scala/kafka/utils/Utils.scala
@@ -27,6 +27,7 @@ import scala.collection._
 import scala.collection.mutable
 import java.util.Properties
 import kafka.common.KafkaException
+import kafka.common.KafkaStorageException
 
 
 /**
@@ -159,7 +160,7 @@ object Utils extends Logging {
    * @param log The log method to use for logging. E.g. logger.warn
    * @param action The action to execute
    */
-  def swallow(log: (Object, Throwable) => Unit, action: => Unit) = {
+  def swallow(log: (Object, Throwable) => Unit, action: => Unit) {
     try {
       action
     } catch {
@@ -528,4 +529,37 @@ object Utils extends Logging {
    */
   def abs(n: Int) = n & 0x7fffffff
   
+  /**
+   * Replace the given string suffix with the new suffix. If the string doesn't end with the given suffix throw an exception.
+   */
+  def replaceSuffix(s: String, oldSuffix: String, newSuffix: String): String = {
+    if(!s.endsWith(oldSuffix))
+      throw new IllegalArgumentException("Expected string to end with '%s' but string is '%s'".format(oldSuffix, s))
+    s.substring(0, s.length - oldSuffix.length) + newSuffix
+  }
+
+  /**
+   * Create a file with the given path
+   * @param path The path to create
+   * @throw KafkaStorageException If the file create fails
+   * @return The created file
+   */
+  def createFile(path: String): File = {
+    val f = new File(path)
+    val created = f.createNewFile()
+    if(!created)
+      throw new KafkaStorageException("Failed to create file %s.".format(path))
+    f
+  }
+  
+  /**
+   * Read a big-endian integer from a byte array
+   */
+  def readInt(bytes: Array[Byte], offset: Int): Int = {
+    ((bytes(offset) & 0xFF) << 24) |
+    ((bytes(offset + 1) & 0xFF) << 16) |
+    ((bytes(offset + 2) & 0xFF) << 8) |
+    (bytes(offset + 3) & 0xFF)
+  }
+  
 }
diff --git a/core/src/main/scala/kafka/utils/VerifiableProperties.scala b/core/src/main/scala/kafka/utils/VerifiableProperties.scala
index d694ba98522..a2ac55ccee9 100644
--- a/core/src/main/scala/kafka/utils/VerifiableProperties.scala
+++ b/core/src/main/scala/kafka/utils/VerifiableProperties.scala
@@ -38,10 +38,7 @@ class VerifiableProperties(val props: Properties) extends Logging {
   /**
    * Read a required integer property value or throw an exception if no such property is found
    */
-  def getInt(name: String): Int = {
-    require(containsKey(name), "Missing required property '" + name + "'")
-    return getInt(name, -1)
-  }
+  def getInt(name: String): Int = getString(name).toInt
 
   def getIntInRange(name: String, range: (Int, Int)): Int = {
     require(containsKey(name), "Missing required property '" + name + "'")
@@ -92,10 +89,7 @@ class VerifiableProperties(val props: Properties) extends Logging {
   /**
    * Read a required long property value or throw an exception if no such property is found
    */
-  def getLong(name: String): Long = {
-    require(containsKey(name), "Missing required property '" + name + "'")
-    return getLong(name, -1)
-  }
+  def getLong(name: String): Long = getString(name).toLong
 
   /**
    * Read an long from the properties instance
@@ -124,6 +118,26 @@ class VerifiableProperties(val props: Properties) extends Logging {
     require(v >= range._1 && v <= range._2, name + " has value " + v + " which is not in the range " + range + ".")
     v
   }
+  
+  /**
+   * Get a required argument as a double
+   * @param name The property name
+   * @return the value
+   * @throw IllegalArgumentException If the given property is not present
+   */
+  def getDouble(name: String): Double = getString(name).toDouble
+  
+  /**
+   * Get an optional argument as a double
+   * @param name The property name
+   * @default The default value for the property if not present
+   */
+  def getDouble(name: String, default: Double): Double = {
+    if(containsKey(name))
+      getDouble(name)
+    else
+      default
+  } 
 
   /**
    * Read a boolean value from the properties instance
@@ -140,6 +154,8 @@ class VerifiableProperties(val props: Properties) extends Logging {
       v.toBoolean
     }
   }
+  
+  def getBoolean(name: String) = getString(name).toBoolean
 
   /**
    * Get a string property, or, if no such property is defined, return the given default value
@@ -162,7 +178,7 @@ class VerifiableProperties(val props: Properties) extends Logging {
   /**
    * Get a Map[String, String] from a property list in the form k1:v2, k2:v2, ...
    */
-  def getMap(name: String, valid: String => Boolean): Map[String, String] = {
+  def getMap(name: String, valid: String => Boolean = s => true): Map[String, String] = {
     try {
       val m = Utils.parseCsvMap(getString(name, ""))
       m.foreach {
@@ -189,4 +205,5 @@ class VerifiableProperties(val props: Properties) extends Logging {
   }
   
   override def toString(): String = props.toString
+ 
 }
diff --git a/core/src/test/scala/other/kafka/StressTestLog.scala b/core/src/test/scala/other/kafka/StressTestLog.scala
index 55429afb0c9..c6e7a571042 100644
--- a/core/src/test/scala/other/kafka/StressTestLog.scala
+++ b/core/src/test/scala/other/kafka/StressTestLog.scala
@@ -34,15 +34,11 @@ object StressTestLog {
     val dir = TestUtils.tempDir()
     val time = new MockTime
     val log = new Log(dir = dir,
-                      scheduler = time.scheduler,
-                      maxSegmentSize = 64*1024*1024,
-                      maxMessageSize = Int.MaxValue, 
-                      flushInterval = Int.MaxValue, 
-                      rollIntervalMs = Long.MaxValue, 
+                      config = LogConfig(segmentSize = 64*1024*1024,
+                                         maxMessageSize = Int.MaxValue,
+                                         maxIndexSize = 1024*1024),
                       needsRecovery = false,
-                      maxIndexSize = 1024*1024,
-                      indexIntervalBytes = 4096,
-                      segmentDeleteDelayMs = 60000,
+                      scheduler = time.scheduler,
                       time = time)
     val writer = new WriterThread(log)
     writer.start()
diff --git a/core/src/test/scala/other/kafka/TestLogCleaning.scala b/core/src/test/scala/other/kafka/TestLogCleaning.scala
new file mode 100644
index 00000000000..d9c721ba3ea
--- /dev/null
+++ b/core/src/test/scala/other/kafka/TestLogCleaning.scala
@@ -0,0 +1,216 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka
+
+import joptsimple.OptionParser
+import java.util.Properties
+import java.util.Random
+import java.io._
+import scala.io.Source
+import scala.io.BufferedSource
+import kafka.producer._
+import kafka.consumer._
+import kafka.serializer._
+import kafka.utils._
+
+/**
+ * This is a torture test that runs against an existing broker. Here is how it works:
+ * 
+ * It produces a series of specially formatted messages to one or more partitions. Each message it produces
+ * it logs out to a text file. The messages have a limited set of keys, so there is duplication in the key space.
+ * 
+ * The broker will clean its log as the test runs.
+ * 
+ * When the specified number of messages have been produced we create a consumer and consume all the messages in the topic
+ * and write that out to another text file.
+ * 
+ * Using a stable unix sort we sort both the producer log of what was sent and the consumer log of what was retrieved by the message key. 
+ * Then we compare the final message in both logs for each key. If this final message is not the same for all keys we
+ * print an error and exit with exit code 1, otherwise we print the size reduction and exit with exit code 0.
+ */
+object TestLogCleaning {
+
+  def main(args: Array[String]) {
+    val parser = new OptionParser
+    val numMessagesOpt = parser.accepts("messages", "The number of messages to send or consume.")
+                               .withRequiredArg
+                               .describedAs("count")
+                               .ofType(classOf[java.lang.Long])
+                               .defaultsTo(Long.MaxValue)
+    val numDupsOpt = parser.accepts("duplicates", "The number of duplicates for each key.")
+                           .withRequiredArg
+                           .describedAs("count")
+                           .ofType(classOf[java.lang.Integer])
+                           .defaultsTo(5)
+    val brokerOpt = parser.accepts("broker", "Url to connect to.")
+                          .withRequiredArg
+                          .describedAs("url")
+                          .ofType(classOf[String])
+    val topicsOpt = parser.accepts("topics", "The number of topics to test.")
+                          .withRequiredArg
+                          .describedAs("count")
+                          .ofType(classOf[java.lang.Integer])
+                          .defaultsTo(1)
+    val zkConnectOpt = parser.accepts("zk", "Zk url.")
+                             .withRequiredArg
+                             .describedAs("url")
+                             .ofType(classOf[String])
+    val sleepSecsOpt = parser.accepts("sleep", "Time to sleep between production and consumption.")
+                             .withRequiredArg
+                             .describedAs("ms")
+                             .ofType(classOf[java.lang.Integer])
+                             .defaultsTo(0)
+    val cleanupOpt = parser.accepts("cleanup", "Delete temp files when done.")
+    
+    val options = parser.parse(args:_*)
+    
+    if(!options.has(brokerOpt) || !options.has(zkConnectOpt) || !options.has(numMessagesOpt)) {
+      parser.printHelpOn(System.err)
+      System.exit(1)
+    }
+    
+    // parse options
+    val messages = options.valueOf(numMessagesOpt).longValue
+    val dups = options.valueOf(numDupsOpt).intValue
+    val brokerUrl = options.valueOf(brokerOpt)
+    val topicCount = options.valueOf(topicsOpt).intValue
+    val zkUrl = options.valueOf(zkConnectOpt)
+    val sleepSecs = options.valueOf(sleepSecsOpt).intValue
+    val cleanup = options.has(cleanupOpt)
+    
+    val testId = new Random().nextInt(Int.MaxValue)
+    val topics = (0 until topicCount).map("log-cleaner-test-" + testId + "-" + _).toArray
+    
+    println("Producing %d messages...".format(messages))
+    val producedDataFile = produceMessages(brokerUrl, topics, messages, dups, cleanup)
+    println("Sleeping for %d seconds...".format(sleepSecs))
+    Thread.sleep(sleepSecs * 1000)
+    println("Consuming messages...")
+    val consumedDataFile = consumeMessages(zkUrl, topics, cleanup)
+    
+    val producedLines = lineCount(producedDataFile)
+    val consumedLines = lineCount(consumedDataFile)
+    val reduction = 1.0 - consumedLines.toDouble/producedLines.toDouble
+    println("%d rows of data produced, %d rows of data consumed (%.1f%% reduction).".format(producedLines, consumedLines, 100 * reduction))
+    
+    println("Validating output files...")
+    validateOutput(externalSort(producedDataFile), externalSort(consumedDataFile))
+    println("All done.")
+  }
+  
+  def lineCount(file: File): Int = io.Source.fromFile(file).getLines.size
+  
+  def validateOutput(produced: BufferedReader, consumed: BufferedReader) {
+    while(true) {
+      val prod = readFinalValue(produced)
+      val cons = readFinalValue(consumed)
+      if(prod == null && cons == null) {
+        return
+      } else if(prod != cons) {
+        System.err.println("Validation failed prod = %s, cons = %s!".format(prod, cons))
+        System.exit(1)
+      }
+    }
+  }
+  
+  def readFinalValue(reader: BufferedReader): (String, Int, Int) = {
+    def readTuple() = {
+      val line = reader.readLine
+      if(line == null)
+        null
+      else
+        line.split("\t")
+    }
+    var prev = readTuple()
+    if(prev == null)
+      return null
+    while(true) {
+      reader.mark(1024)
+      val curr = readTuple()
+      if(curr == null || curr(0) != prev(0) || curr(1) != prev(1)) {
+        reader.reset()
+        return (prev(0), prev(1).toInt, prev(2).toInt)
+      } else {
+        prev = curr
+      }
+    }
+    return null
+  }
+  
+  def externalSort(file: File): BufferedReader = {
+    val builder = new ProcessBuilder("sort", "--key=1,2", "--stable", "--buffer-size=20%", file.getAbsolutePath)
+    val process = builder.start()
+    new BufferedReader(new InputStreamReader(process.getInputStream()))
+  }
+  
+  def produceMessages(brokerUrl: String, 
+                      topics: Array[String], 
+                      messages: Long, 
+                      dups: Int, 
+                      cleanup: Boolean): File = {
+    val producerProps = new Properties
+    producerProps.setProperty("producer.type", "async")
+    producerProps.setProperty("broker.list", brokerUrl)
+    producerProps.setProperty("serializer.class", classOf[StringEncoder].getName)
+    producerProps.setProperty("key.serializer.class", classOf[StringEncoder].getName)
+    producerProps.setProperty("queue.enqueue.timeout.ms", "-1")
+    producerProps.setProperty("batch.size", 1000.toString)
+    val producer = new Producer[String, String](new ProducerConfig(producerProps))
+    val rand = new Random(1)
+    val keyCount = (messages / dups).toInt
+    val producedFile = File.createTempFile("kafka-log-cleaner-produced-", ".txt")
+    if(cleanup)
+      producedFile.deleteOnExit()
+    val producedWriter = new BufferedWriter(new FileWriter(producedFile), 1024*1024)
+    for(i <- 0L until (messages * topics.length)) {
+      val topic = topics((i % topics.length).toInt)
+      val key = rand.nextInt(keyCount)
+      producer.send(KeyedMessage(topic = topic, key = key.toString, message = i.toString))
+      producedWriter.write("%s\t%s\t%s\n".format(topic, key, i))
+    }
+    producedWriter.close()
+    producer.close()
+    producedFile
+  }
+  
+  def consumeMessages(zkUrl: String, topics: Array[String], cleanup: Boolean): File = {
+    val consumerProps = new Properties
+    consumerProps.setProperty("group.id", "log-cleaner-test-" + new Random().nextInt(Int.MaxValue))
+    consumerProps.setProperty("zk.connect", zkUrl)
+    consumerProps.setProperty("consumer.timeout.ms", (5*1000).toString)
+    val connector = new ZookeeperConsumerConnector(new ConsumerConfig(consumerProps))
+    val streams = connector.createMessageStreams(topics.map(topic => (topic, 1)).toMap, new StringDecoder, new StringDecoder)
+    val consumedFile = File.createTempFile("kafka-log-cleaner-consumed-", ".txt")
+    if(cleanup)
+      consumedFile.deleteOnExit()
+    val consumedWriter = new BufferedWriter(new FileWriter(consumedFile))
+    for(topic <- topics) {
+      val stream = streams(topic).head
+      try {
+        for(item <- stream)
+          consumedWriter.write("%s\t%s\t%s\n".format(topic, item.key, item.message))
+      } catch {
+        case e: ConsumerTimeoutException => 
+      }
+    }
+    consumedWriter.close()
+    connector.shutdown()
+    consumedFile
+  }
+  
+}
\ No newline at end of file
diff --git a/core/src/test/scala/other/kafka/TestLogPerformance.scala b/core/src/test/scala/other/kafka/TestLogPerformance.scala
index a7b661a2e53..d91011eb2f6 100644
--- a/core/src/test/scala/other/kafka/TestLogPerformance.scala
+++ b/core/src/test/scala/other/kafka/TestLogPerformance.scala
@@ -34,7 +34,8 @@ object TestLogPerformance {
     val config = new KafkaConfig(props)
     val dir = TestUtils.tempDir()
     val scheduler = new KafkaScheduler(1)
-    val log = new Log(dir, scheduler, 50*1024*1024, config.messageMaxBytes, 5000000, config.logRollHours*60*60*1000L, needsRecovery = false, segmentDeleteDelayMs = 0, time = SystemTime)
+    val logConfig = LogConfig()
+    val log = new Log(dir, logConfig, needsRecovery = false, scheduler = scheduler, time = SystemTime)
     val bytes = new Array[Byte](messageSize)
     new java.util.Random().nextBytes(bytes)
     val message = new Message(bytes)
diff --git a/core/src/test/scala/unit/kafka/log/CleanerTest.scala b/core/src/test/scala/unit/kafka/log/CleanerTest.scala
new file mode 100644
index 00000000000..cce2319d23b
--- /dev/null
+++ b/core/src/test/scala/unit/kafka/log/CleanerTest.scala
@@ -0,0 +1,227 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+import junit.framework.Assert._
+import org.scalatest.junit.JUnitSuite
+import org.junit.{After, Before, Test}
+import java.nio._
+import java.io.File
+import scala.collection._
+import kafka.common._
+import kafka.utils._
+import kafka.message._
+
+/**
+ * Unit tests for the log cleaning logic
+ */
+class CleanerTest extends JUnitSuite {
+  
+  val dir = TestUtils.tempDir()
+  val logConfig = LogConfig(segmentSize=1024, maxIndexSize=1024, dedupe=true)
+  val time = new MockTime()
+  val throttler = new Throttler(desiredRatePerSec = Double.MaxValue, checkIntervalMs = Long.MaxValue, time = time)
+  
+  @After
+  def teardown() {
+    Utils.rm(dir)
+  }
+  
+  /**
+   * Test simple log cleaning
+   */
+  @Test
+  def testCleanSegments() {
+    val cleaner = makeCleaner(Int.MaxValue)
+    val log = makeLog(config = logConfig.copy(segmentSize = 1024))
+    
+    // append messages to the log until we have four segments
+    while(log.numberOfSegments < 4)
+      log.append(messages(log.logEndOffset.toInt, log.logEndOffset.toInt))
+    val keysFound = keysInLog(log)
+    assertEquals((0L until log.logEndOffset), keysFound)
+    
+    // pretend we have the following keys
+    val keys = immutable.ListSet(1, 3, 5, 7, 9)
+    val map = new FakeOffsetMap(Int.MaxValue)
+    keys.foreach(k => map.put(key(k), Long.MaxValue))
+    
+    // clean the log
+    cleaner.cleanSegments(log, log.logSegments.take(3).toSeq, map, 0)
+    val shouldRemain = keysInLog(log).filter(!keys.contains(_))
+    assertEquals(shouldRemain, keysInLog(log))
+  }
+  
+  /* extract all the keys from a log */
+  def keysInLog(log: Log): Iterable[Int] = 
+    log.logSegments.flatMap(s => s.log.map(m => Utils.readString(m.message.key).toInt))
+  
+  
+  /**
+   * Test that a truncation during cleaning throws an OptimisticLockFailureException
+   */
+  @Test
+  def testCleanSegmentsWithTruncation() {
+    val cleaner = makeCleaner(Int.MaxValue)
+    val log = makeLog(config = logConfig.copy(segmentSize = 1024))
+    
+    // append messages to the log until we have four segments
+    while(log.numberOfSegments < 2)
+      log.append(messages(log.logEndOffset.toInt, log.logEndOffset.toInt))
+      
+    log.truncateTo(log.logEndOffset-2)
+    val keys = keysInLog(log)
+    val map = new FakeOffsetMap(Int.MaxValue)
+    keys.foreach(k => map.put(key(k), Long.MaxValue))
+    intercept[OptimisticLockFailureException] {
+      cleaner.cleanSegments(log, log.logSegments.take(3).toSeq, map, 0)
+    }
+  }
+  
+  /**
+   * Validate the logic for grouping log segments together for cleaning
+   */
+  @Test
+  def testSegmentGrouping() {
+    val cleaner = makeCleaner(Int.MaxValue)
+    val log = makeLog(config = logConfig.copy(segmentSize = 300, indexInterval = 1))
+    
+    // append some messages to the log
+    var i = 0
+    while(log.numberOfSegments < 10) {
+      log.append(TestUtils.singleMessageSet("hello".getBytes))
+      i += 1
+    }
+    
+    // grouping by very large values should result in a single group with all the segments in it
+    var groups = cleaner.groupSegmentsBySize(log.logSegments, maxSize = Int.MaxValue, maxIndexSize = Int.MaxValue)
+    assertEquals(1, groups.size)
+    assertEquals(log.numberOfSegments, groups(0).size)
+    checkSegmentOrder(groups)
+    
+    // grouping by very small values should result in all groups having one entry
+    groups = cleaner.groupSegmentsBySize(log.logSegments, maxSize = 1, maxIndexSize = Int.MaxValue)
+    assertEquals(log.numberOfSegments, groups.size)
+    assertTrue("All groups should be singletons.", groups.forall(_.size == 1))
+    checkSegmentOrder(groups)
+    groups = cleaner.groupSegmentsBySize(log.logSegments, maxSize = Int.MaxValue, maxIndexSize = 1)
+    assertEquals(log.numberOfSegments, groups.size)
+    assertTrue("All groups should be singletons.", groups.forall(_.size == 1))
+    checkSegmentOrder(groups)
+
+    val groupSize = 3
+    
+    // check grouping by log size
+    val logSize = log.logSegments.take(groupSize).map(_.size).sum.toInt + 1
+    groups = cleaner.groupSegmentsBySize(log.logSegments, maxSize = logSize, maxIndexSize = Int.MaxValue)
+    checkSegmentOrder(groups)
+    assertTrue("All but the last group should be the target size.", groups.dropRight(1).forall(_.size == groupSize))
+    
+    // check grouping by index size
+    val indexSize = log.logSegments.take(groupSize).map(_.index.sizeInBytes()).sum + 1
+    groups = cleaner.groupSegmentsBySize(log.logSegments, maxSize = Int.MaxValue, maxIndexSize = indexSize)
+    checkSegmentOrder(groups)
+    assertTrue("All but the last group should be the target size.", groups.dropRight(1).forall(_.size == groupSize))
+  }
+  
+  private def checkSegmentOrder(groups: Seq[Seq[LogSegment]]) {
+    val offsets = groups.flatMap(_.map(_.baseOffset))
+    assertEquals("Offsets should be in increasing order.", offsets.sorted, offsets)
+  }
+  
+  /**
+   * Test building an offset map off the log
+   */
+  @Test
+  def testBuildOffsetMap() {
+    val map = new FakeOffsetMap(1000)
+    val log = makeLog()
+    val cleaner = makeCleaner(Int.MaxValue)
+    val start = 0
+    val end = 500
+    val offsets = writeToLog(log, (start until end) zip (start until end))
+    def checkRange(map: FakeOffsetMap, start: Int, end: Int) {
+      val endOffset = cleaner.buildOffsetMap(log, start, end, map) + 1
+      assertEquals("Last offset should be the end offset.", end, endOffset)
+      assertEquals("Should have the expected number of messages in the map.", end-start, map.size)
+      for(i <- start until end)
+        assertEquals("Should find all the keys", i.toLong, map.get(key(i)))
+      assertEquals("Should not find a value too small", -1L, map.get(key(start-1)))
+      assertEquals("Should not find a value too large", -1L, map.get(key(end)))
+    }
+    val segments = log.logSegments.toSeq
+    checkRange(map, 0, segments(1).baseOffset.toInt)
+    checkRange(map, segments(1).baseOffset.toInt, segments(3).baseOffset.toInt)
+    checkRange(map, segments(3).baseOffset.toInt, log.logEndOffset.toInt)
+  }
+  
+  /**
+   * Test that we don't exceed the maximum capacity of the offset map, that is that an offset map
+   * with a max size of 1000 will only clean 1000 new entries even if more than that are available.
+   */
+  @Test
+  def testBuildOffsetMapOverCapacity() {
+    val map = new FakeOffsetMap(1000)
+    val log = makeLog()
+    val cleaner = makeCleaner(Int.MaxValue)
+    val vals = 0 until 1001
+    val offsets = writeToLog(log, vals zip vals)
+    val lastOffset = cleaner.buildOffsetMap(log, vals.start, vals.end, map)
+    assertEquals("Shouldn't go beyond the capacity of the offset map.", 1000, lastOffset)
+  }
+  
+  def makeLog(dir: File = dir, config: LogConfig = logConfig) =
+    new Log(dir = dir, config = config, needsRecovery = false, scheduler = time.scheduler, time = time)
+  
+  def makeCleaner(capacity: Int) = 
+    new Cleaner(id = 0, new FakeOffsetMap(capacity), ioBufferSize = 64*1024, maxIoBufferSize = 64*1024, throttler = throttler, time = time)
+  
+  def writeToLog(log: Log, seq: Iterable[(Int, Int)]): Iterable[Long] = {
+    for((key, value) <- seq)
+      yield log.append(messages(key, value)).firstOffset
+  }
+  
+  def key(id: Int) = ByteBuffer.wrap(id.toString.getBytes)
+  
+  def messages(key: Int, value: Int) = 
+    new ByteBufferMessageSet(new Message(key=key.toString.getBytes, bytes=value.toString.getBytes))
+  
+}
+
+class FakeOffsetMap(val capacity: Int) extends OffsetMap {
+  val map = new java.util.HashMap[String, Long]()
+  
+  private def keyFor(key: ByteBuffer) = 
+    new String(Utils.readBytes(key.duplicate), "UTF-8")
+  
+  def put(key: ByteBuffer, offset: Long): Unit = 
+    map.put(keyFor(key), offset)
+  
+  def get(key: ByteBuffer): Long = {
+    val k = keyFor(key)
+    if(map.containsKey(k))
+      map.get(k)
+    else
+      -1L
+  }
+  
+  def clear() = map.clear()
+  
+  def size: Int = map.size
+  
+}
\ No newline at end of file
diff --git a/core/src/test/scala/unit/kafka/log/LogCleanerIntegrationTest.scala b/core/src/test/scala/unit/kafka/log/LogCleanerIntegrationTest.scala
new file mode 100644
index 00000000000..5a489f9eafe
--- /dev/null
+++ b/core/src/test/scala/unit/kafka/log/LogCleanerIntegrationTest.scala
@@ -0,0 +1,117 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+import java.io.File
+import scala.collection._
+import org.junit._
+import kafka.common.TopicAndPartition
+import kafka.utils._
+import kafka.message._
+import org.scalatest.junit.JUnitSuite
+import junit.framework.Assert._
+
+/**
+ * This is an integration test that tests the fully integrated log cleaner
+ */
+class LogCleanerIntegrationTest extends JUnitSuite {
+  
+  val time = new MockTime()
+  val segmentSize = 100
+  val deleteDelay = 1000
+  val logName = "log"
+  val logDir = TestUtils.tempDir()
+  var counter = 0
+  val topics = Array(TopicAndPartition("log", 0), TopicAndPartition("log", 1), TopicAndPartition("log", 2))
+  
+  @Test
+  def cleanerTest() {
+    val cleaner = makeCleaner(parts = 3)
+    val log = cleaner.logs.get(topics(0))
+
+    val appends = writeDups(numKeys = 100, numDups = 3, log)
+    val startSize = log.size
+    cleaner.startup()
+    
+    val lastCleaned = log.activeSegment.baseOffset
+    // wait until we clean up to base_offset of active segment - minDirtyMessages
+    cleaner.awaitCleaned("log", 0, lastCleaned)
+    
+    val read = readFromLog(log)
+    assertEquals("Contents of the map shouldn't change.", appends.toMap, read.toMap)
+    assertTrue(startSize > log.size)
+    
+    // write some more stuff and validate again
+    val appends2 = appends ++ writeDups(numKeys = 100, numDups = 3, log)
+    val lastCleaned2 = log.activeSegment.baseOffset
+    cleaner.awaitCleaned("log", 0, lastCleaned2)
+    val read2 = readFromLog(log)
+    assertEquals("Contents of the map shouldn't change.", appends2.toMap, read2.toMap)
+    
+    cleaner.shutdown()
+  }
+  
+  def readFromLog(log: Log): Iterable[(Int, Int)] = {
+    for(segment <- log.logSegments; message <- segment.log) yield {
+      val key = Utils.readString(message.message.key).toInt
+      val value = Utils.readString(message.message.payload).toInt
+      key -> value
+    }
+  }
+  
+  def writeDups(numKeys: Int, numDups: Int, log: Log): Seq[(Int, Int)] = {
+    for(dup <- 0 until numDups; key <- 0 until numKeys) yield {
+      val count = counter
+      val appendInfo = log.append(TestUtils.singleMessageSet(payload = counter.toString.getBytes, key = key.toString.getBytes), assignOffsets = true)
+      counter += 1
+      (key, count)
+    }
+  }
+    
+  @After
+  def teardown() {
+    Utils.rm(logDir)
+  }
+  
+  /* create a cleaner instance and logs with the given parameters */
+  def makeCleaner(parts: Int, 
+                  minDirtyMessages: Int = 0, 
+                  numThreads: Int = 1,
+                  defaultPolicy: String = "dedupe",
+                  policyOverrides: Map[String, String] = Map()): LogCleaner = {
+    
+    // create partitions and add them to the pool
+    val logs = new Pool[TopicAndPartition, Log]()
+    for(i <- 0 until parts) {
+      val dir = new File(logDir, "log-" + i)
+      dir.mkdirs()
+      val log = new Log(dir = dir,
+                        LogConfig(segmentSize = segmentSize, maxIndexSize = 100*1024, fileDeleteDelayMs = deleteDelay, dedupe = true),
+                        needsRecovery = false,
+                        scheduler = time.scheduler,
+                        time = time)
+      logs.put(TopicAndPartition("log", i), log)      
+    }
+  
+    new LogCleaner(CleanerConfig(numThreads = numThreads),
+                   logDirs = Array(logDir),
+                   logs = logs,
+                   time = time)
+  }
+
+}
\ No newline at end of file
diff --git a/core/src/test/scala/unit/kafka/log/LogManagerTest.scala b/core/src/test/scala/unit/kafka/log/LogManagerTest.scala
index f48c709d8e1..fad3baac1c6 100644
--- a/core/src/test/scala/unit/kafka/log/LogManagerTest.scala
+++ b/core/src/test/scala/unit/kafka/log/LogManagerTest.scala
@@ -29,21 +29,18 @@ class LogManagerTest extends JUnit3Suite {
 
   val time: MockTime = new MockTime()
   val maxRollInterval = 100
-  val maxLogAgeHours = 10
+  val maxLogAgeMs = 10*60*60*1000
+  val logConfig = LogConfig(segmentSize = 1024, maxIndexSize = 4096, retentionMs = maxLogAgeMs)
   var logDir: File = null
   var logManager: LogManager = null
-  var config: KafkaConfig = null
   val name = "kafka"
   val veryLargeLogFlushInterval = 10000000L
+  val cleanerConfig = CleanerConfig(enableCleaner = false)
 
   override def setUp() {
     super.setUp()
-    config = new KafkaConfig(TestUtils.createBrokerConfig(0, -1)) {
-                   override val logSegmentBytes = 1024
-                   override val logFlushIntervalMessages = 10000
-                   override val logRetentionHours = maxLogAgeHours
-                 }
-    logManager = new LogManager(config, time.scheduler, time)
+    logDir = TestUtils.tempDir()
+    logManager = new LogManager(Array(logDir), Map(), logConfig, cleanerConfig, 1000L, 1000L, time.scheduler, time)
     logManager.startup
     logDir = logManager.logDirs(0)
   }
@@ -62,7 +59,7 @@ class LogManagerTest extends JUnit3Suite {
   @Test
   def testCreateLog() {
     val log = logManager.getOrCreateLog(name, 0)
-    val logFile = new File(config.logDirs(0), name + "-0")
+    val logFile = new File(logDir, name + "-0")
     assertTrue(logFile.exists)
     log.append(TestUtils.singleMessageSet("test".getBytes()))
   }
@@ -74,7 +71,7 @@ class LogManagerTest extends JUnit3Suite {
   def testGetNonExistentLog() {
     val log = logManager.getLog(name, 0)
     assertEquals("No log should be found.", None, log)
-    val logFile = new File(config.logDirs(0), name + "-0")
+    val logFile = new File(logDir, name + "-0")
     assertTrue(!logFile.exists)
   }
 
@@ -94,9 +91,9 @@ class LogManagerTest extends JUnit3Suite {
     
     log.logSegments.foreach(_.log.file.setLastModified(time.milliseconds))
     
-    time.sleep(maxLogAgeHours*60*60*1000 + 1)
+    time.sleep(maxLogAgeMs + 1)
     assertEquals("Now there should only be only one segment in the index.", 1, log.numberOfSegments)
-    time.sleep(log.segmentDeleteDelayMs + 1)
+    time.sleep(log.config.fileDeleteDelayMs + 1)
     assertEquals("Files should have been deleted", log.numberOfSegments * 2, log.dir.list.length)
     assertEquals("Should get empty fetch off new log.", 0, log.read(offset+1, 1024).sizeInBytes)
 
@@ -116,14 +113,10 @@ class LogManagerTest extends JUnit3Suite {
   @Test
   def testCleanupSegmentsToMaintainSize() {
     val setSize = TestUtils.singleMessageSet("test".getBytes()).sizeInBytes
-    val props = TestUtils.createBrokerConfig(0, -1)
     logManager.shutdown()
-    config = new KafkaConfig(props) {
-      override val logSegmentBytes = (10 * (setSize - 1)) // each segment will be 10 messages
-      override val logRetentionBytes = (5 * 10 * setSize + 10).asInstanceOf[Long]
-      override val logRollHours = maxRollInterval
-    }
-    logManager = new LogManager(config, time.scheduler, time)
+
+    val config = logConfig.copy(segmentSize = 10 * (setSize - 1), retentionSize = 5L * 10L * setSize + 10L)
+    logManager = new LogManager(Array(logDir), Map(), config, cleanerConfig, 1000L, 1000L, time.scheduler, time)
     logManager.startup
 
     // create a log
@@ -138,13 +131,12 @@ class LogManagerTest extends JUnit3Suite {
       offset = info.firstOffset
     }
 
-    // should be exactly 100 full segments + 1 new empty one
-    assertEquals("Check we have the expected number of segments.", numMessages * setSize / config.logSegmentBytes, log.numberOfSegments)
+    assertEquals("Check we have the expected number of segments.", numMessages * setSize / config.segmentSize, log.numberOfSegments)
 
     // this cleanup shouldn't find any expired segments but should delete some to reduce size
     time.sleep(logManager.InitialTaskDelayMs)
     assertEquals("Now there should be exactly 6 segments", 6, log.numberOfSegments)
-    time.sleep(log.segmentDeleteDelayMs + 1)
+    time.sleep(log.config.fileDeleteDelayMs + 1)
     assertEquals("Files should have been deleted", log.numberOfSegments * 2, log.dir.list.length)
     assertEquals("Should get empty fetch off new log.", 0, log.read(offset + 1, 1024).sizeInBytes)
     try {
@@ -162,14 +154,9 @@ class LogManagerTest extends JUnit3Suite {
    */
   @Test
   def testTimeBasedFlush() {
-    val props = TestUtils.createBrokerConfig(0, -1)
     logManager.shutdown()
-    config = new KafkaConfig(props) {
-                   override val logFlushSchedulerIntervalMs = 1000
-                   override val logFlushIntervalMs = 1000
-                   override val logFlushIntervalMessages = Int.MaxValue
-                 }
-    logManager = new LogManager(config, time.scheduler, time)
+    val config = logConfig.copy(flushMs = 1000)
+    logManager = new LogManager(Array(logDir), Map(), config, cleanerConfig, 1000L, 1000L, time.scheduler, time)
     logManager.startup
     val log = logManager.getOrCreateLog(name, 0)
     val lastFlush = log.lastFlushTime
@@ -187,13 +174,11 @@ class LogManagerTest extends JUnit3Suite {
   @Test
   def testLeastLoadedAssignment() {
     // create a log manager with multiple data directories
-    val props = TestUtils.createBrokerConfig(0, -1)
-    val dirs = Seq(TestUtils.tempDir().getAbsolutePath, 
-                   TestUtils.tempDir().getAbsolutePath, 
-                   TestUtils.tempDir().getAbsolutePath)
-    props.put("log.dirs", dirs.mkString(","))
+    val dirs = Array(TestUtils.tempDir(), 
+                     TestUtils.tempDir(), 
+                     TestUtils.tempDir())
     logManager.shutdown()
-    logManager = new LogManager(new KafkaConfig(props), time.scheduler, time)
+    logManager = new LogManager(dirs, Map(), logConfig, cleanerConfig, 1000L, 1000L, time.scheduler, time)
     
     // verify that logs are always assigned to the least loaded partition
     for(partition <- 0 until 20) {
@@ -209,7 +194,7 @@ class LogManagerTest extends JUnit3Suite {
    */
   def testTwoLogManagersUsingSameDirFails() {
     try {
-      new LogManager(logManager.config, time.scheduler, time)
+      new LogManager(Array(logDir), Map(), logConfig, cleanerConfig, 1000L, 1000L, time.scheduler, time)
       fail("Should not be able to create a second log manager instance with the same data directory")
     } catch {
       case e: KafkaException => // this is good 
diff --git a/core/src/test/scala/unit/kafka/log/LogSegmentTest.scala b/core/src/test/scala/unit/kafka/log/LogSegmentTest.scala
index bffe4a451a0..a185ce4f7b2 100644
--- a/core/src/test/scala/unit/kafka/log/LogSegmentTest.scala
+++ b/core/src/test/scala/unit/kafka/log/LogSegmentTest.scala
@@ -160,6 +160,21 @@ class LogSegmentTest extends JUnit3Suite {
     assertEquals(53, seg.nextOffset())
   }
   
+  /**
+   * Test that we can change the file suffixes for the log and index files
+   */
+  @Test
+  def testChangeFileSuffixes() {
+    val seg = createSegment(40)
+    val logFile = seg.log.file
+    val indexFile = seg.index.file
+    seg.changeFileSuffixes("", ".deleted")
+    assertEquals(logFile.getAbsolutePath + ".deleted", seg.log.file.getAbsolutePath)
+    assertEquals(indexFile.getAbsolutePath + ".deleted", seg.index.file.getAbsolutePath)
+    assertTrue(seg.log.file.exists)
+    assertTrue(seg.index.file.exists)
+  }
+  
   /**
    * Create a segment with some data and an index. Then corrupt the index,
    * and recover the segment, the entries should all be readable.
diff --git a/core/src/test/scala/unit/kafka/log/LogTest.scala b/core/src/test/scala/unit/kafka/log/LogTest.scala
index 0fc74fa2d4c..23e0e6562dc 100644
--- a/core/src/test/scala/unit/kafka/log/LogTest.scala
+++ b/core/src/test/scala/unit/kafka/log/LogTest.scala
@@ -34,6 +34,7 @@ class LogTest extends JUnitSuite {
   var logDir: File = null
   val time = new MockTime
   var config: KafkaConfig = null
+  val logConfig = LogConfig()
 
   @Before
   def setUp() {
@@ -61,12 +62,15 @@ class LogTest extends JUnitSuite {
   @Test
   def testTimeBasedLogRoll() {
     val set = TestUtils.singleMessageSet("test".getBytes())
-    val rollMs = 1 * 60 * 60L
     val time: MockTime = new MockTime()
 
     // create a log
-    val log = new Log(logDir, time.scheduler, 1000, config.messageMaxBytes, 1000, rollMs, needsRecovery = false, time = time)
-    time.sleep(rollMs + 1)
+    val log = new Log(logDir, 
+                      logConfig.copy(segmentMs = 1 * 60 * 60L), 
+                      needsRecovery = false, 
+                      scheduler = time.scheduler, 
+                      time = time)
+    time.sleep(log.config.segmentMs + 1)
 
     // segment age is less than its limit
     log.append(set)
@@ -76,13 +80,13 @@ class LogTest extends JUnitSuite {
     assertEquals("There should still be exactly one segment.", 1, log.numberOfSegments)
 
     for(numSegments <- 2 until 4) {
-      time.sleep(rollMs + 1)
+      time.sleep(log.config.segmentMs + 1)
       log.append(set)
       assertEquals("Changing time beyond rollMs and appending should create a new segment.", numSegments, log.numberOfSegments)
     }
 
     val numSegments = log.numberOfSegments
-    time.sleep(rollMs + 1)
+    time.sleep(log.config.segmentMs + 1)
     log.append(new ByteBufferMessageSet())
     assertEquals("Appending an empty message set should not roll log even if succient time has passed.", numSegments, log.numberOfSegments)
   }
@@ -95,10 +99,10 @@ class LogTest extends JUnitSuite {
     val set = TestUtils.singleMessageSet("test".getBytes)
     val setSize = set.sizeInBytes
     val msgPerSeg = 10
-    val logFileSize = msgPerSeg * (setSize - 1) // each segment will be 10 messages
+    val segmentSize = msgPerSeg * (setSize - 1) // each segment will be 10 messages
 
     // create a log
-    val log = new Log(logDir, time.scheduler, logFileSize, config.messageMaxBytes, 1000, 10000, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = segmentSize), needsRecovery = false, time.scheduler, time = time)
     assertEquals("There should be exactly 1 segment.", 1, log.numberOfSegments)
 
     // segments expire in size
@@ -114,7 +118,7 @@ class LogTest extends JUnitSuite {
   @Test
   def testLoadEmptyLog() {
     createEmptyLogs(logDir, 0)
-    val log = new Log(logDir, time.scheduler, 1024, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig, needsRecovery = false, time.scheduler, time = time)
     log.append(TestUtils.singleMessageSet("test".getBytes))
   }
 
@@ -123,7 +127,7 @@ class LogTest extends JUnitSuite {
    */
   @Test
   def testAppendAndReadWithSequentialOffsets() {
-    val log = new Log(logDir, time.scheduler, 71, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = 71), needsRecovery = false, time.scheduler, time = time)
     val messages = (0 until 100 by 2).map(id => new Message(id.toString.getBytes)).toArray
     
     for(i <- 0 until messages.length)
@@ -142,7 +146,7 @@ class LogTest extends JUnitSuite {
    */
   @Test
   def testAppendAndReadWithNonSequentialOffsets() {
-    val log = new Log(logDir, time.scheduler, 71, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = 71), needsRecovery = false, time.scheduler, time = time)
     val messageIds = ((0 until 50) ++ (50 until 200 by 7)).toArray
     val messages = messageIds.map(id => new Message(id.toString.getBytes))
     
@@ -165,7 +169,7 @@ class LogTest extends JUnitSuite {
    */
   @Test
   def testReadAtLogGap() {
-    val log = new Log(logDir, time.scheduler, 300, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = 300), needsRecovery = false, time.scheduler, time = time)
     
     // keep appending until we have two segments with only a single message in the second segment
     while(log.numberOfSegments == 1)
@@ -185,7 +189,7 @@ class LogTest extends JUnitSuite {
   @Test
   def testReadOutOfRange() {
     createEmptyLogs(logDir, 1024)
-    val log = new Log(logDir, time.scheduler, 1024, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = 1024), needsRecovery = false, time.scheduler, time = time)
     assertEquals("Reading just beyond end of log should produce 0 byte read.", 0, log.read(1024, 1000).sizeInBytes)
     try {
       log.read(0, 1024)
@@ -208,7 +212,7 @@ class LogTest extends JUnitSuite {
   @Test
   def testLogRolls() {
     /* create a multipart log with 100 messages */
-    val log = new Log(logDir, time.scheduler, 100, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = 100), needsRecovery = false, time.scheduler, time = time)
     val numMessages = 100
     val messageSets = (0 until numMessages).map(i => TestUtils.singleMessageSet(i.toString.getBytes))
     val offsets = messageSets.map(log.append(_).firstOffset)
@@ -232,8 +236,8 @@ class LogTest extends JUnitSuite {
   @Test
   def testCompressedMessages() {
     /* this log should roll after every messageset */
-    val log = new Log(logDir, time.scheduler, 10, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
-
+    val log = new Log(logDir, logConfig.copy(segmentSize = 10), needsRecovery = false, time.scheduler, time = time)
+    
     /* append 2 compressed message sets, each with two messages giving offsets 0, 1, 2, 3 */
     log.append(new ByteBufferMessageSet(DefaultCompressionCodec, new Message("hello".getBytes), new Message("there".getBytes)))
     log.append(new ByteBufferMessageSet(DefaultCompressionCodec, new Message("alpha".getBytes), new Message("beta".getBytes)))
@@ -255,7 +259,7 @@ class LogTest extends JUnitSuite {
     for(messagesToAppend <- List(0, 1, 25)) {
       logDir.mkdirs()
       // first test a log segment starting at 0
-      val log = new Log(logDir, time.scheduler, 100, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+      val log = new Log(logDir, logConfig.copy(segmentSize = 100), needsRecovery = false, time.scheduler, time = time)
       for(i <- 0 until messagesToAppend)
         log.append(TestUtils.singleMessageSet(i.toString.getBytes))
       
@@ -289,7 +293,7 @@ class LogTest extends JUnitSuite {
 
     // append messages to log
     val maxMessageSize = second.sizeInBytes - 1
-    val log = new Log(logDir, time.scheduler, 100, maxMessageSize, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(maxMessageSize = maxMessageSize), needsRecovery = false, time.scheduler, time = time)
 
     // should be able to append the small message
     log.append(first)
@@ -311,7 +315,8 @@ class LogTest extends JUnitSuite {
     val messageSize = 100
     val segmentSize = 7 * messageSize
     val indexInterval = 3 * messageSize
-    var log = new Log(logDir, time.scheduler, segmentSize, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, indexIntervalBytes = indexInterval, maxIndexSize = 4096)
+    val config = logConfig.copy(segmentSize = segmentSize, indexInterval = indexInterval, maxIndexSize = 4096)
+    var log = new Log(logDir, config, needsRecovery = false, time.scheduler, time)
     for(i <- 0 until numMessages)
       log.append(TestUtils.singleMessageSet(TestUtils.randomBytes(messageSize)))
     assertEquals("After appending %d messages to an empty log, the log end offset should be %d".format(numMessages, numMessages), numMessages, log.logEndOffset)
@@ -319,15 +324,14 @@ class LogTest extends JUnitSuite {
     val numIndexEntries = log.activeSegment.index.entries
     log.close()
     
-    // test non-recovery case
-    log = new Log(logDir, time.scheduler, segmentSize, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = false, indexIntervalBytes = indexInterval, maxIndexSize = 4096)
+    log = new Log(logDir, config, needsRecovery = false, time.scheduler, time)
     assertEquals("Should have %d messages when log is reopened w/o recovery".format(numMessages), numMessages, log.logEndOffset)
     assertEquals("Should have same last index offset as before.", lastIndexOffset, log.activeSegment.index.lastOffset)
     assertEquals("Should have same number of index entries as before.", numIndexEntries, log.activeSegment.index.entries)
     log.close()
     
     // test recovery case
-    log = new Log(logDir, time.scheduler, segmentSize, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = true, indexIntervalBytes = indexInterval, maxIndexSize = 4096)
+    log = new Log(logDir, config, needsRecovery = true, time.scheduler, time)
     assertEquals("Should have %d messages when log is reopened with recovery".format(numMessages), numMessages, log.logEndOffset)
     assertEquals("Should have same last index offset as before.", lastIndexOffset, log.activeSegment.index.lastOffset)
     assertEquals("Should have same number of index entries as before.", numIndexEntries, log.activeSegment.index.entries)
@@ -341,7 +345,8 @@ class LogTest extends JUnitSuite {
   def testIndexRebuild() {
     // publish the messages and close the log
     val numMessages = 200
-    var log = new Log(logDir, time.scheduler, 200, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = true, indexIntervalBytes = 1, maxIndexSize = 4096)
+    val config = logConfig.copy(segmentSize = 200, indexInterval = 1)
+    var log = new Log(logDir, config, needsRecovery = true, time.scheduler, time)
     for(i <- 0 until numMessages)
       log.append(TestUtils.singleMessageSet(TestUtils.randomBytes(10)))
     val indexFiles = log.logSegments.map(_.index.file)
@@ -351,8 +356,7 @@ class LogTest extends JUnitSuite {
     indexFiles.foreach(_.delete())
     
     // reopen the log
-    log = new Log(logDir, time.scheduler, 200, config.messageMaxBytes, 1000, config.logRollHours*60*60*1000L, needsRecovery = true, indexIntervalBytes = 1, maxIndexSize = 4096)
-    
+    log = new Log(logDir, config, needsRecovery = true, time.scheduler, time)    
     assertEquals("Should have %d messages when log is reopened".format(numMessages), numMessages, log.logEndOffset)
     for(i <- 0 until numMessages)
       assertEquals(i, log.read(i, 100, None).head.offset)
@@ -367,10 +371,10 @@ class LogTest extends JUnitSuite {
     val set = TestUtils.singleMessageSet("test".getBytes())
     val setSize = set.sizeInBytes
     val msgPerSeg = 10
-    val logFileSize = msgPerSeg * (setSize - 1) // each segment will be 10 messages
+    val segmentSize = msgPerSeg * (setSize - 1) // each segment will be 10 messages
 
     // create a log
-    val log = new Log(logDir, time.scheduler, logFileSize, config.messageMaxBytes, 1000, 10000, needsRecovery = false, time = time)
+    val log = new Log(logDir, logConfig.copy(segmentSize = segmentSize), needsRecovery = false, scheduler = time.scheduler, time = time)
     assertEquals("There should be exactly 1 segment.", 1, log.numberOfSegments)
 
     for (i<- 1 to msgPerSeg)
@@ -421,8 +425,9 @@ class LogTest extends JUnitSuite {
     val set = TestUtils.singleMessageSet("test".getBytes())
     val setSize = set.sizeInBytes
     val msgPerSeg = 10
-    val logFileSize = msgPerSeg * (setSize - 1) // each segment will be 10 messages
-    val log = new Log(logDir, time.scheduler, logFileSize, config.messageMaxBytes, 1000, 10000, needsRecovery = false, time = time)
+    val segmentSize = msgPerSeg * (setSize - 1) // each segment will be 10 messages
+    val config = logConfig.copy(segmentSize = segmentSize)
+    val log = new Log(logDir, config, needsRecovery = false, scheduler = time.scheduler, time = time)
     assertEquals("There should be exactly 1 segment.", 1, log.numberOfSegments)
     for (i<- 1 to msgPerSeg)
       log.append(set)
@@ -430,10 +435,10 @@ class LogTest extends JUnitSuite {
     for (i<- 1 to msgPerSeg)
       log.append(set)
     assertEquals("There should be exactly 2 segment.", 2, log.numberOfSegments)
-    assertEquals("The index of the first segment should be trim to empty", 0, log.logSegments.toList(0).index.maxEntries)
+    assertEquals("The index of the first segment should be trimmed to empty", 0, log.logSegments.toList(0).index.maxEntries)
     log.truncateTo(0)
     assertEquals("There should be exactly 1 segment.", 1, log.numberOfSegments)
-    assertEquals("The index of segment 1 should be resized to maxIndexSize", log.maxIndexSize/8, log.logSegments.toList(0).index.maxEntries)
+    assertEquals("The index of segment 1 should be resized to maxIndexSize", log.config.maxIndexSize/8, log.logSegments.toList(0).index.maxEntries)
     for (i<- 1 to msgPerSeg)
       log.append(set)
     assertEquals("There should be exactly 1 segment.", 1, log.numberOfSegments)
@@ -449,12 +454,12 @@ class LogTest extends JUnitSuite {
     
     val set = TestUtils.singleMessageSet("test".getBytes())
     val log = new Log(logDir, 
+                      logConfig.copy(segmentSize = set.sizeInBytes * 5, 
+                                     maxIndexSize = 1000, 
+                                     indexInterval = 1),
+                      needsRecovery = false,
                       time.scheduler,
-                      maxSegmentSize = set.sizeInBytes * 5, 
-                      maxMessageSize = config.messageMaxBytes,
-                      maxIndexSize = 1000,
-                      indexIntervalBytes = 1, 
-                      needsRecovery = false)
+                      time)
     
     assertTrue("The first index file should have been replaced with a larger file", bogusIndex1.length > 0)
     assertFalse("The second index file should have been deleted.", bogusIndex2.exists)
@@ -472,27 +477,26 @@ class LogTest extends JUnitSuite {
   @Test
   def testReopenThenTruncate() {
     val set = TestUtils.singleMessageSet("test".getBytes())
+    val config = logConfig.copy(segmentSize = set.sizeInBytes * 5, 
+                                maxIndexSize = 1000, 
+                                indexInterval = 10000)
 
     // create a log
     var log = new Log(logDir, 
+                      config,
+                      needsRecovery = true,
                       time.scheduler,
-                      maxSegmentSize = set.sizeInBytes * 5, 
-                      maxMessageSize = config.messageMaxBytes,
-                      maxIndexSize = 1000,
-                      indexIntervalBytes = 10000, 
-                      needsRecovery = true)
+                      time)
     
     // add enough messages to roll over several segments then close and re-open and attempt to truncate
     for(i <- 0 until 100)
       log.append(set)
     log.close()
     log = new Log(logDir, 
+                  config,
+                  needsRecovery = true,
                   time.scheduler,
-                  maxSegmentSize = set.sizeInBytes * 5, 
-                  maxMessageSize = config.messageMaxBytes,
-                  maxIndexSize = 1000,
-                  indexIntervalBytes = 10000, 
-                  needsRecovery = true)
+                  time)
     log.truncateTo(3)
     assertEquals("All but one segment should be deleted.", 1, log.numberOfSegments)
     assertEquals("Log end offset should be 3.", 3, log.logEndOffset)
@@ -505,14 +509,15 @@ class LogTest extends JUnitSuite {
   def testAsyncDelete() {
     val set = TestUtils.singleMessageSet("test".getBytes())
     val asyncDeleteMs = 1000
-    val log = new Log(logDir, 
+    val config = logConfig.copy(segmentSize = set.sizeInBytes * 5, 
+                                fileDeleteDelayMs = asyncDeleteMs, 
+                                maxIndexSize = 1000, 
+                                indexInterval = 10000)
+    val log = new Log(logDir,
+                      config,
+                      needsRecovery = true,                      
                       time.scheduler,
-                      maxSegmentSize = set.sizeInBytes * 5, 
-                      maxMessageSize = config.messageMaxBytes,
-                      maxIndexSize = 1000, 
-                      indexIntervalBytes = 10000, 
-                      segmentDeleteDelayMs = asyncDeleteMs,
-                      needsRecovery = true)
+                      time)
     
     // append some messages to create some segments
     for(i <- 0 until 100)
@@ -520,15 +525,20 @@ class LogTest extends JUnitSuite {
     
     // files should be renamed
     val segments = log.logSegments.toArray
+    val oldFiles = segments.map(_.log.file) ++ segments.map(_.index.file)
     log.deleteOldSegments((s) => true)
     
     assertEquals("Only one segment should remain.", 1, log.numberOfSegments)
-    val renamed = segments.map(segment => new File(segment.log.file.getPath + Log.DeletedFileSuffix))
-    assertTrue("Files should all be renamed to .deleted.", renamed.forall(_.exists))
+    assertTrue("All log and index files should end in .deleted", segments.forall(_.log.file.getName.endsWith(Log.DeletedFileSuffix)) && 
+                                                                 segments.forall(_.index.file.getName.endsWith(Log.DeletedFileSuffix)))
+    assertTrue("The .deleted files should still be there.", segments.forall(_.log.file.exists) &&
+                                                            segments.forall(_.index.file.exists))
+    assertTrue("The original file should be gone.", oldFiles.forall(!_.exists))
     
     // when enough time passes the files should be deleted
+    val deletedFiles = segments.map(_.log.file) ++ segments.map(_.index.file)
     time.sleep(asyncDeleteMs + 1)
-    assertTrue("Files should all be gone.", renamed.forall(!_.exists))
+    assertTrue("Files should all be gone.", deletedFiles.forall(!_.exists))
   }
   
   /**
@@ -537,13 +547,12 @@ class LogTest extends JUnitSuite {
   @Test
   def testOpenDeletesObsoleteFiles() {
     val set = TestUtils.singleMessageSet("test".getBytes())
-    var log = new Log(logDir, 
+    val config = logConfig.copy(segmentSize = set.sizeInBytes * 5, maxIndexSize = 1000)
+    var log = new Log(logDir,
+                      config,
+                      needsRecovery = false,
                       time.scheduler,
-                      maxSegmentSize = set.sizeInBytes * 5, 
-                      maxMessageSize = config.messageMaxBytes,
-                      maxIndexSize = 1000, 
-                      indexIntervalBytes = 10000, 
-                      needsRecovery = false)
+                      time)
     
     // append some messages to create some segments
     for(i <- 0 until 100)
@@ -553,12 +562,10 @@ class LogTest extends JUnitSuite {
     log.close()
     
     log = new Log(logDir, 
+                  config,
+                  needsRecovery = false,
                   time.scheduler,
-                  maxSegmentSize = set.sizeInBytes * 5, 
-                  maxMessageSize = config.messageMaxBytes,
-                  maxIndexSize = 1000, 
-                  indexIntervalBytes = 10000,
-                  needsRecovery = false)
+                  time)
     assertEquals("The deleted segments should be gone.", 1, log.numberOfSegments)
   }
   
diff --git a/core/src/test/scala/unit/kafka/log/OffsetMapTest.scala b/core/src/test/scala/unit/kafka/log/OffsetMapTest.scala
new file mode 100644
index 00000000000..99a0c4bfefb
--- /dev/null
+++ b/core/src/test/scala/unit/kafka/log/OffsetMapTest.scala
@@ -0,0 +1,87 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ * 
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kafka.log
+
+import java.nio._
+import org.junit._
+import org.scalatest.junit.JUnitSuite
+import junit.framework.Assert._
+
+class OffsetMapTest extends JUnitSuite {
+  
+  @Test
+  def testBasicValidation() {
+    validateMap(10)
+    validateMap(100)
+    validateMap(1000)
+  }
+  
+  @Test
+  def testClear() {
+    val map = new SkimpyOffsetMap(4000, 0.75)
+    for(i <- 0 until 10)
+      map.put(key(i), i)
+    for(i <- 0 until 10)
+      assertEquals(i.toLong, map.get(key(i)))
+    map.clear()
+    for(i <- 0 until 10)
+      assertEquals(map.get(key(i)), -1L)
+  }
+  
+  @Test
+  def testCapacity() {
+    val map = new SkimpyOffsetMap(1024, 0.75)
+    var i = 0
+    while(map.size < map.capacity) {
+      map.put(key(i), i)
+      i += 1
+    }
+    // now the map is full, it should throw an exception
+    intercept[IllegalStateException] {
+      map.put(key(i), i)
+    }
+  }
+  
+  def key(key: Int) = ByteBuffer.wrap(key.toString.getBytes)
+  
+  def validateMap(items: Int) {
+    val map = new SkimpyOffsetMap(items * 2 * 24, 0.75)
+    for(i <- 0 until items)
+      map.put(key(i), i)
+    var misses = 0
+    for(i <- 0 until items) {
+      map.get(key(i)) match {
+        case -1L => misses += 1
+        case offset => assertEquals(i.toLong, offset) 
+      }
+    }
+    println("Miss rate: " + (misses.toDouble / items))
+  }
+  
+}
+
+object OffsetMapTest {
+  def main(args: Array[String]) {
+    if(args.length != 1) {
+      System.err.println("USAGE: java OffsetMapTest size")
+      System.exit(1)
+    }
+    val test = new OffsetMapTest()
+    test.validateMap(args(0).toInt)
+  }
+}
\ No newline at end of file
diff --git a/core/src/test/scala/unit/kafka/server/HighwatermarkPersistenceTest.scala b/core/src/test/scala/unit/kafka/server/HighwatermarkPersistenceTest.scala
index b6095857e39..8a3e33b5a39 100644
--- a/core/src/test/scala/unit/kafka/server/HighwatermarkPersistenceTest.scala
+++ b/core/src/test/scala/unit/kafka/server/HighwatermarkPersistenceTest.scala
@@ -16,13 +16,14 @@
 */
 package kafka.server
 
-import kafka.log.LogManager
+import kafka.log._
+import java.io.File
 import org.I0Itec.zkclient.ZkClient
 import org.scalatest.junit.JUnit3Suite
 import org.easymock.EasyMock
 import org.junit._
 import org.junit.Assert._
-import kafka.common.KafkaException
+import kafka.common._
 import kafka.cluster.Replica
 import kafka.utils._
 
@@ -30,7 +31,14 @@ class HighwatermarkPersistenceTest extends JUnit3Suite {
 
   val configs = TestUtils.createBrokerConfigs(2).map(new KafkaConfig(_))
   val topic = "foo"
-  val logManagers = configs.map(config => new LogManager(config, new KafkaScheduler(1), new MockTime))
+  val logManagers = configs.map(config => new LogManager(logDirs = config.logDirs.map(new File(_)).toArray,
+                                                         topicConfigs = Map(),
+                                                         defaultConfig = LogConfig(),
+                                                         cleanerConfig = CleanerConfig(),
+                                                         flushCheckMs = 30000,
+                                                         retentionCheckMs = 30000,
+                                                         scheduler = new KafkaScheduler(1),
+                                                         time = new MockTime))
     
   @After
   def teardown() {
@@ -133,7 +141,7 @@ class HighwatermarkPersistenceTest extends JUnit3Suite {
   }
 
   def hwmFor(replicaManager: ReplicaManager, topic: String, partition: Int): Long = {
-    replicaManager.highWatermarkCheckpoints(replicaManager.config.logDirs(0)).read(topic, partition)
+    replicaManager.highWatermarkCheckpoints(replicaManager.config.logDirs(0)).read.getOrElse(TopicAndPartition(topic, partition), 0L)
   }
   
 }
\ No newline at end of file
diff --git a/core/src/test/scala/unit/kafka/server/LogOffsetTest.scala b/core/src/test/scala/unit/kafka/server/LogOffsetTest.scala
index e3752cb191d..f857171ef68 100644
--- a/core/src/test/scala/unit/kafka/server/LogOffsetTest.scala
+++ b/core/src/test/scala/unit/kafka/server/LogOffsetTest.scala
@@ -205,7 +205,7 @@ class LogOffsetTest extends JUnit3Suite with ZooKeeperTestHarness {
     props.put("enable.zookeeper", "false")
     props.put("num.partitions", "20")
     props.put("log.retention.hours", "10")
-    props.put("log.cleanup.interval.mins", "5")
+    props.put("log.retention.check.interval.ms", (5*1000*60).toString)
     props.put("log.segment.bytes", logSize.toString)
     props.put("zk.connect", zkConnect.toString)
     props
diff --git a/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala b/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala
index cd724a337f8..48487e84c15 100644
--- a/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala
+++ b/core/src/test/scala/unit/kafka/server/LogRecoveryTest.scala
@@ -18,11 +18,13 @@ package kafka.server
 
 import org.scalatest.junit.JUnit3Suite
 import org.junit.Assert._
+import java.io.File
 import kafka.admin.CreateTopicCommand
 import kafka.utils.TestUtils._
 import kafka.utils.IntEncoder
 import kafka.utils.{Utils, TestUtils}
 import kafka.zk.ZooKeeperTestHarness
+import kafka.common._
 import kafka.producer.{ProducerConfig, KeyedMessage, Producer}
 
 class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
@@ -44,8 +46,8 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
   val message = "hello"
 
   var producer: Producer[Int, String] = null
-  var hwFile1: HighwaterMarkCheckpoint = new HighwaterMarkCheckpoint(configProps1.logDirs(0))
-  var hwFile2: HighwaterMarkCheckpoint = new HighwaterMarkCheckpoint(configProps2.logDirs(0))
+  var hwFile1: OffsetCheckpoint = new OffsetCheckpoint(new File(configProps1.logDirs(0), ReplicaManager.HighWatermarkFilename))
+  var hwFile2: OffsetCheckpoint = new OffsetCheckpoint(new File(configProps2.logDirs(0), ReplicaManager.HighWatermarkFilename))
   var servers: Seq[KafkaServer] = Seq.empty[KafkaServer]
   
   val producerProps = getProducerConfig(TestUtils.getBrokerListStrFromConfigs(configs), 64*1024, 100000, 10000)
@@ -80,9 +82,9 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
 
     servers.foreach(server => server.replicaManager.checkpointHighWatermarks())
     producer.close()
-    val leaderHW = hwFile1.read(topic, 0)
+    val leaderHW = hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L)
     assertEquals(numMessages, leaderHW)
-    val followerHW = hwFile2.read(topic, 0)
+    val followerHW = hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L)
     assertEquals(numMessages, followerHW)
     servers.foreach(server => { server.shutdown(); Utils.rm(server.config.logDirs(0))})
   }
@@ -104,7 +106,7 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     // NOTE: this is to avoid transient test failures
     assertTrue("Leader could be broker 0 or broker 1", (leader.getOrElse(-1) == 0) || (leader.getOrElse(-1) == 1))
     
-    assertEquals(0L, hwFile1.read(topic, 0))
+    assertEquals(0L, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
 
     sendMessages(1)
     Thread.sleep(1000)
@@ -112,7 +114,7 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
 
     // kill the server hosting the preferred replica
     server1.shutdown()
-    assertEquals(hw, hwFile1.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
 
     // check if leader moves to the other server
     leader = waitUntilLeaderIsElectedOrChanged(zkClient, topic, partitionId, 500, leader)
@@ -125,10 +127,10 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     assertTrue("Leader must remain on broker 1, in case of zookeeper session expiration it can move to broker 0",
       leader.isDefined && (leader.get == 0 || leader.get == 1))
 
-    assertEquals(hw, hwFile1.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
     // since server 2 was never shut down, the hw value of 30 is probably not checkpointed to disk yet
     server2.shutdown()
-    assertEquals(hw, hwFile2.read(topic, 0))
+    assertEquals(hw, hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L))
 
     server2.startup()
     leader = waitUntilLeaderIsElectedOrChanged(zkClient, topic, partitionId, 500, leader)
@@ -144,8 +146,8 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     // shutdown the servers to allow the hw to be checkpointed
     servers.foreach(server => server.shutdown())
     producer.close()
-    assertEquals(hw, hwFile1.read(topic, 0))
-    assertEquals(hw, hwFile2.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
+    assertEquals(hw, hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L))
     servers.foreach(server => Utils.rm(server.config.logDirs))
   }
 
@@ -155,8 +157,8 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     server2 = TestUtils.createServer(configs.last)
     servers ++= List(server1, server2)
 
-    hwFile1 = new HighwaterMarkCheckpoint(server1.config.logDirs(0))
-    hwFile2 = new HighwaterMarkCheckpoint(server2.config.logDirs(0))
+    hwFile1 = new OffsetCheckpoint(new File(server1.config.logDirs(0), ReplicaManager.HighWatermarkFilename))
+    hwFile2 = new OffsetCheckpoint(new File(server2.config.logDirs(0), ReplicaManager.HighWatermarkFilename))
 
     producer = new Producer[Int, String](new ProducerConfig(producerProps))
 
@@ -176,9 +178,9 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     // shutdown the servers to allow the hw to be checkpointed
     servers.foreach(server => server.shutdown())
     producer.close()
-    val leaderHW = hwFile1.read(topic, 0)
+    val leaderHW = hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L)
     assertEquals(hw, leaderHW)
-    val followerHW = hwFile2.read(topic, 0)
+    val followerHW = hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L)
     assertEquals(hw, followerHW)
     servers.foreach(server => Utils.rm(server.config.logDirs))
   }
@@ -189,8 +191,8 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     server2 = TestUtils.createServer(configs.last)
     servers ++= List(server1, server2)
 
-    hwFile1 = new HighwaterMarkCheckpoint(server1.config.logDirs(0))
-    hwFile2 = new HighwaterMarkCheckpoint(server2.config.logDirs(0))
+    hwFile1 = new OffsetCheckpoint(new File(server1.config.logDirs(0), ReplicaManager.HighWatermarkFilename))
+    hwFile2 = new OffsetCheckpoint(new File(server2.config.logDirs(0), ReplicaManager.HighWatermarkFilename))
 
     producer = new Producer[Int, String](new ProducerConfig(producerProps))
 
@@ -212,21 +214,21 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     // kill the server hosting the preferred replica
     server1.shutdown()
     server2.shutdown()
-    assertEquals(hw, hwFile1.read(topic, 0))
-    assertEquals(hw, hwFile2.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
+    assertEquals(hw, hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L))
 
     server2.startup()
     // check if leader moves to the other server
     leader = waitUntilLeaderIsElectedOrChanged(zkClient, topic, partitionId, 500, leader)
     assertEquals("Leader must move to broker 1", 1, leader.getOrElse(-1))
 
-    assertEquals(hw, hwFile1.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
 
     // bring the preferred replica back
     server1.startup()
 
-    assertEquals(hw, hwFile1.read(topic, 0))
-    assertEquals(hw, hwFile2.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
+    assertEquals(hw, hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L))
 
     sendMessages(2)
     hw += 2
@@ -237,8 +239,8 @@ class LogRecoveryTest extends JUnit3Suite with ZooKeeperTestHarness {
     // shutdown the servers to allow the hw to be checkpointed
     servers.foreach(server => server.shutdown())
     producer.close()
-    assertEquals(hw, hwFile1.read(topic, 0))
-    assertEquals(hw, hwFile2.read(topic, 0))
+    assertEquals(hw, hwFile1.read.getOrElse(TopicAndPartition(topic, 0), 0L))
+    assertEquals(hw, hwFile2.read.getOrElse(TopicAndPartition(topic, 0), 0L))
     servers.foreach(server => Utils.rm(server.config.logDirs))
   }
 
diff --git a/core/src/test/scala/unit/kafka/server/SimpleFetchTest.scala b/core/src/test/scala/unit/kafka/server/SimpleFetchTest.scala
index 46193899492..571e2df48bd 100644
--- a/core/src/test/scala/unit/kafka/server/SimpleFetchTest.scala
+++ b/core/src/test/scala/unit/kafka/server/SimpleFetchTest.scala
@@ -68,7 +68,6 @@ class SimpleFetchTest extends JUnit3Suite {
 
     val logManager = EasyMock.createMock(classOf[kafka.log.LogManager])
     EasyMock.expect(logManager.getLog(topic, partitionId)).andReturn(Some(log)).anyTimes()
-    EasyMock.expect(logManager.config).andReturn(configs.head).anyTimes()
     EasyMock.replay(logManager)
 
     val replicaManager = EasyMock.createMock(classOf[kafka.server.ReplicaManager])
@@ -135,7 +134,6 @@ class SimpleFetchTest extends JUnit3Suite {
 
     val logManager = EasyMock.createMock(classOf[kafka.log.LogManager])
     EasyMock.expect(logManager.getLog(topic, 0)).andReturn(Some(log)).anyTimes()
-    EasyMock.expect(logManager.config).andReturn(configs.head).anyTimes()
     EasyMock.replay(logManager)
 
     val replicaManager = EasyMock.createMock(classOf[kafka.server.ReplicaManager])
diff --git a/core/src/test/scala/unit/kafka/utils/MockScheduler.scala b/core/src/test/scala/unit/kafka/utils/MockScheduler.scala
index 4853f2bbbfc..d5896ed4d3b 100644
--- a/core/src/test/scala/unit/kafka/utils/MockScheduler.scala
+++ b/core/src/test/scala/unit/kafka/utils/MockScheduler.scala
@@ -32,7 +32,6 @@ import java.util.concurrent.TimeUnit
  *   
  * Incrementing the time to the exact next execution time of a task will result in that task executing (it as if execution itself takes no time).
  */
-@nonthreadsafe
 class MockScheduler(val time: Time) extends Scheduler {
   
   /* a priority queue of tasks ordered by next execution time */
@@ -41,7 +40,9 @@ class MockScheduler(val time: Time) extends Scheduler {
   def startup() {}
   
   def shutdown() {
-    tasks.clear()
+    this synchronized {
+      tasks.clear()
+    }
   }
   
   /**
@@ -50,23 +51,26 @@ class MockScheduler(val time: Time) extends Scheduler {
    * If you are using the scheduler associated with a MockTime instance this call be triggered automatically.
    */
   def tick() {
-    val now = time.milliseconds
-    while(!tasks.isEmpty && tasks.head.nextExecution <= now) {
-      /* pop and execute the task with the lowest next execution time */
-      val curr = tasks.head
-      this.tasks = tasks.tail
-      curr.fun()
-      /* if the task is periodic, reschedule it and re-enqueue */
-      if(curr.periodic) {
-        curr.nextExecution += curr.period
-        this.tasks += curr
+    this synchronized {
+      val now = time.milliseconds
+      while(!tasks.isEmpty && tasks.head.nextExecution <= now) {
+        /* pop and execute the task with the lowest next execution time */
+        val curr = tasks.dequeue
+        curr.fun()
+        /* if the task is periodic, reschedule it and re-enqueue */
+        if(curr.periodic) {
+          curr.nextExecution += curr.period
+          this.tasks += curr
+        }
       }
     }
   }
   
   def schedule(name: String, fun: ()=>Unit, delay: Long = 0, period: Long = -1, unit: TimeUnit = TimeUnit.MILLISECONDS) {
-    tasks += MockTask(name, fun, time.milliseconds + delay, period = period)
-    tick()
+    this synchronized {
+      tasks += MockTask(name, fun, time.milliseconds + delay, period = period)
+      tick()
+    }
   }
   
 }
diff --git a/core/src/test/scala/unit/kafka/utils/TestUtils.scala b/core/src/test/scala/unit/kafka/utils/TestUtils.scala
index 5547d63a405..d12d24ef457 100644
--- a/core/src/test/scala/unit/kafka/utils/TestUtils.scala
+++ b/core/src/test/scala/unit/kafka/utils/TestUtils.scala
@@ -43,6 +43,8 @@ import kafka.common.TopicAndPartition
  * Utility functions to help with testing
  */
 object TestUtils extends Logging {
+  
+  val IoTmpDir = System.getProperty("java.io.tmpdir")
 
   val Letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
   val Digits = "0123456789"
@@ -74,8 +76,7 @@ object TestUtils extends Logging {
    * Create a temporary directory
    */
   def tempDir(): File = {
-    val ioDir = System.getProperty("java.io.tmpdir")
-    val f = new File(ioDir, "kafka-" + random.nextInt(1000000))
+    val f = new File(IoTmpDir, "kafka-" + random.nextInt(1000000))
     f.mkdirs()
     f.deleteOnExit()
     f
@@ -154,8 +155,8 @@ object TestUtils extends Logging {
    * Wrap the message in a message set
    * @param payload The bytes of the message
    */
-  def singleMessageSet(payload: Array[Byte], codec: CompressionCodec = NoCompressionCodec) =
-    new ByteBufferMessageSet(compressionCodec = codec, messages = new Message(payload))
+  def singleMessageSet(payload: Array[Byte], codec: CompressionCodec = NoCompressionCodec, key: Array[Byte] = null) =
+    new ByteBufferMessageSet(compressionCodec = codec, messages = new Message(payload, key))
 
   /**
    * Generate an array of random bytes
@@ -497,7 +498,7 @@ object TestUtils extends Logging {
 }
 
 object TestZKUtils {
-  val zookeeperConnect = "127.0.0.1:2182"
+  val zookeeperConnect = "127.0.0.1:" + TestUtils.choosePort()
 }
 
 class IntEncoder(props: VerifiableProperties = null) extends Encoder[Int] {
diff --git a/core/src/test/scala/unit/kafka/utils/UtilsTest.scala b/core/src/test/scala/unit/kafka/utils/UtilsTest.scala
index cce6c8ea29f..48dd3352dda 100644
--- a/core/src/test/scala/unit/kafka/utils/UtilsTest.scala
+++ b/core/src/test/scala/unit/kafka/utils/UtilsTest.scala
@@ -19,6 +19,7 @@ package kafka.utils
 
 import java.util.Arrays
 import java.nio.ByteBuffer
+import java.io._
 import org.apache.log4j.Logger
 import org.scalatest.junit.JUnitSuite
 import org.junit.Test
@@ -61,6 +62,25 @@ class UtilsTest extends JUnitSuite {
       assertTrue(Arrays.equals(bytes, Utils.readBytes(ByteBuffer.wrap(bytes))))
     }
   }
+  
+  @Test
+  def testReplaceSuffix() {
+    assertEquals("blah.foo.text", Utils.replaceSuffix("blah.foo.txt", ".txt", ".text"))
+    assertEquals("blah.foo", Utils.replaceSuffix("blah.foo.txt", ".txt", ""))
+    assertEquals("txt.txt", Utils.replaceSuffix("txt.txt.txt", ".txt", ""))
+    assertEquals("foo.txt", Utils.replaceSuffix("foo", "", ".txt"))
+  }
+  
+  @Test
+  def testReadInt() {
+    val values = Array(0, 1, -1, Byte.MaxValue, Short.MaxValue, 2 * Short.MaxValue, Int.MaxValue/2, Int.MinValue/2, Int.MaxValue, Int.MinValue, Int.MaxValue)
+    val buffer = ByteBuffer.allocate(4 * values.size)
+    for(i <- 0 until values.length) {
+      buffer.putInt(i*4, values(i))
+      assertEquals("Written value should match read value.", values(i), Utils.readInt(buffer.array, i*4))
+    }
+
+  }
 
   @Test
   def testCsvList() {