kafka-1571; MetadataTest hangs; patched by Jun Rao; reviewed by Guozhang Wang

clients/src/test/java/org/apache/kafka/clients/producer/MetadataTest.java

@@ -17,6 +17,7 @@ import static org.junit.Assert.assertTrue;
 
 import org.apache.kafka.clients.producer.internals.Metadata;
 import org.apache.kafka.common.Cluster;
+import org.apache.kafka.common.errors.TimeoutException;
 import org.apache.kafka.test.TestUtils;
 import org.junit.Test;
 
@@ -40,8 +41,6 @@ public class MetadataTest {
         Thread t2 = asyncFetch(topic);
         assertTrue("Awaiting update", t1.isAlive());
         assertTrue("Awaiting update", t2.isAlive());
-        // keep updating the metadata until no need to
-        while (metadata.timeToNextUpdate(time) == 0)
         metadata.update(TestUtils.singletonCluster(topic, 1), time);
         t1.join();
         t2.join();
@@ -53,8 +52,13 @@ public class MetadataTest {
     private Thread asyncFetch(final String topic) {
         Thread thread = new Thread() {
             public void run() {
-                while (metadata.fetch().partitionsForTopic(topic) == null)
-                    metadata.awaitUpdate(metadata.requestUpdate(), Long.MAX_VALUE);
+                while (metadata.fetch().partitionsForTopic(topic) == null) {
+                    try {
+                        metadata.awaitUpdate(metadata.requestUpdate(), refreshBackoffMs);
+                    } catch(TimeoutException e) {
+                        // let it go
+                    }
+                }
             }
         };
         thread.start();