Blergh. We made shutdown synchronized. But decrementing the requests is
also synchronized and called from a different thread. So yeah, deadlock.

Can you open a ticket for this? This came in with ZOOKEEPER-1907

C

On Wed, Dec 16, 2015 at 2:46 PM, Ted Yu <[email protected]> wrote:

> Hi,
> HBase recently upgraded to zookeeper 3.4.7
>
> In one of the tests, TestSplitLogManager, there is reproducible hang at the
> end of the test.
> Below is snippet from stack trace related to zookeeper:
>
> "main-EventThread" daemon prio=5 tid=0x00007fd27488a800 nid=0x6f1f waiting
> on condition [0x000000011834b000]
>    java.lang.Thread.State: WAITING (parking)
>   at sun.misc.Unsafe.park(Native Method)
>   - parking to wait for  <0x00000007c5b8d3a0> (a
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
>   at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
>   at
>
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
>   at
> java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
>   at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:501)
>
> "main-SendThread(localhost:59510)" daemon prio=5 tid=0x00007fd274eb4000
> nid=0x9513 waiting on condition [0x0000000118042000]
>    java.lang.Thread.State: TIMED_WAITING (sleeping)
>   at java.lang.Thread.sleep(Native Method)
>   at
>
> org.apache.zookeeper.client.StaticHostProvider.next(StaticHostProvider.java:101)
>   at
>
> org.apache.zookeeper.ClientCnxn$SendThread.startConnect(ClientCnxn.java:997)
>   at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1060)
>
> "SyncThread:0" prio=5 tid=0x00007fd274d02000 nid=0x730f waiting for monitor
> entry [0x00000001170ac000]
>    java.lang.Thread.State: BLOCKED (on object monitor)
>   at
>
> org.apache.zookeeper.server.ZooKeeperServer.decInProcess(ZooKeeperServer.java:512)
>   - waiting to lock <0x00000007c5b62128> (a
> org.apache.zookeeper.server.ZooKeeperServer)
>   at
>
> org.apache.zookeeper.server.FinalRequestProcessor.processRequest(FinalRequestProcessor.java:144)
>   at
>
> org.apache.zookeeper.server.SyncRequestProcessor.flush(SyncRequestProcessor.java:200)
>   at
>
> org.apache.zookeeper.server.SyncRequestProcessor.run(SyncRequestProcessor.java:131)
>
> "main-EventThread" daemon prio=5 tid=0x00007fd2753a3800 nid=0x711b waiting
> on condition [0x0000000117a30000]
>    java.lang.Thread.State: WAITING (parking)
>   at sun.misc.Unsafe.park(Native Method)
>   - parking to wait for  <0x00000007c9b106b8> (a
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
>   at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
>   at
>
> java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2043)
>   at
> java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:442)
>   at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:501)
>
> "main" prio=5 tid=0x00007fd276000000 nid=0x1903 in Object.wait()
> [0x0000000108aa1000]
>    java.lang.Thread.State: WAITING (on object monitor)
>   at java.lang.Object.wait(Native Method)
>   - waiting on <*0x00000007c5b66400*> (a
> org.apache.zookeeper.server.SyncRequestProcessor)
>   at java.lang.Thread.join(Thread.java:1281)
>   - locked <*0x00000007c5b66400*> (a
> org.apache.zookeeper.server.SyncRequestProcessor)
>   at java.lang.Thread.join(Thread.java:1355)
>   at
>
> org.apache.zookeeper.server.SyncRequestProcessor.shutdown(SyncRequestProcessor.java:213)
>   at
>
> org.apache.zookeeper.server.PrepRequestProcessor.shutdown(PrepRequestProcessor.java:770)
>   at
>
> org.apache.zookeeper.server.ZooKeeperServer.shutdown(ZooKeeperServer.java:478)
>   - locked <0x00000007c5b62128> (a
> org.apache.zookeeper.server.ZooKeeperServer)
>   at
>
> org.apache.zookeeper.server.NIOServerCnxnFactory.shutdown(NIOServerCnxnFactory.java:266)
>   at
>
> org.apache.hadoop.hbase.zookeeper.MiniZooKeeperCluster.shutdown(MiniZooKeeperCluster.java:301)
>
> Note the bold address in the last hunk which seems to indicate some form of
> deadlock.
>
> I can send the full stack trace upon request.
> When reverting to 3.4.6, the test passes.
>
> Comment / hint is welcome.
>
> Cheers
>

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