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https://issues.apache.org/jira/browse/KAFKA-1764?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14211781#comment-14211781
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Chris Cope commented on KAFKA-1764:
-----------------------------------
Why do builds always break just as I put the kids to sleep and grab a glass of
wine?
> ZookeeperConsumerConnector could put multiple shutdownCommand to the same
> data chunk queue.
> -------------------------------------------------------------------------------------------
>
> Key: KAFKA-1764
> URL: https://issues.apache.org/jira/browse/KAFKA-1764
> Project: Kafka
> Issue Type: Bug
> Reporter: Jiangjie Qin
> Assignee: Jiangjie Qin
> Attachments: KAFKA-1764.patch, KAFKA-1764_2014-11-12_14:05:35.patch
>
>
> In ZookeeperConsumerConnector shutdown(), we could potentially put multiple
> shutdownCommand into the same data chunk queue, provided the topics are
> sharing the same data chunk queue in topicThreadIdAndQueues.
> From email thread to document:
> In ZookeeperConsumerConnector shutdown(), we could potentially put
> multiple shutdownCommand into the same data chunk queue, provided the
> topics are sharing the same data chunk queue in topicThreadIdAndQueues.
> In our case, we only have 1 consumer stream for all the topics, the data
> chunk queue capacity is set to 1. The execution sequence causing problem is
> as below:
> 1. ZookeeperConsumerConnector shutdown() is called, it tries to put
> shutdownCommand for each queue in topicThreadIdAndQueues. Since we only
> have 1 queue, multiple shutdownCommand will be put into the queue.
> 2. In sendShutdownToAllQueues(), between queue.clean() and
> queue.put(shutdownCommand), consumer iterator receives the shutdownCommand
> and put it back into the data chunk queue. After that,
> ZookeeperConsumerConnector tries to put another shutdownCommand into the
> data chunk queue but will block forever.
> The thread stack trace is as below:
> {code}
> "Thread-23" #58 prio=5 os_prio=0 tid=0x00007ff440004800 nid=0x40a waiting
> on condition [0x00007ff4f0124000]
> java.lang.Thread.State: WAITING (parking)
> at sun.misc.Unsafe.park(Native Method)
> - parking to wait for <0x0000000680b96bf0> (a
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
> at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
> at
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
> at
> java.util.concurrent.LinkedBlockingQueue.put(LinkedBlockingQueue.java:350)
> at
> kafka.consumer.ZookeeperConsumerConnector$$anonfun$sendShutdownToAllQueues$1.apply(ZookeeperConsumerConnector.scala:262)
> at
> kafka.consumer.ZookeeperConsumerConnector$$anonfun$sendShutdownToAllQueues$1.apply(ZookeeperConsumerConnector.scala:259)
> at scala.collection.Iterator$class.foreach(Iterator.scala:727)
> at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
> at
> scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
> at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
> at
> kafka.consumer.ZookeeperConsumerConnector.sendShutdownToAllQueues(ZookeeperConsumerConnector.scala:259)
> at
> kafka.consumer.ZookeeperConsumerConnector.liftedTree1$1(ZookeeperConsumerConnector.scala:199)
> at
> kafka.consumer.ZookeeperConsumerConnector.shutdown(ZookeeperConsumerConnector.scala:192)
> - locked <0x0000000680dd5848> (a java.lang.Object)
> at
> kafka.tools.MirrorMaker$$anonfun$cleanShutdown$1.apply(MirrorMaker.scala:185)
> at
> kafka.tools.MirrorMaker$$anonfun$cleanShutdown$1.apply(MirrorMaker.scala:185)
> at scala.collection.immutable.List.foreach(List.scala:318)
> at kafka.tools.MirrorMaker$.cleanShutdown(MirrorMaker.scala:185)
> {code}
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