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From "Arina Ielchiieva (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-5599) Notify StatusHandlerListener that batch sending has failed even if channel is still open
Date Tue, 20 Jun 2017 11:36:00 GMT
Arina Ielchiieva created DRILL-5599:
---------------------------------------

             Summary: Notify StatusHandlerListener that batch sending has failed even if channel
is still open 
                 Key: DRILL-5599
                 URL: https://issues.apache.org/jira/browse/DRILL-5599
             Project: Apache Drill
          Issue Type: Bug
    Affects Versions: 1.11.0
            Reporter: Arina Ielchiieva
            Assignee: Arina Ielchiieva


*Issue*
Queries stay in CANCELLATION_REQUESTED state after connection with client was interrupted.
Jstack shows that threads for such queries are blocked and waiting to semaphore to be released.
{noformat}
"26b70318-ddde-9ead-eee2-0828da97b59f:frag:0:0" daemon prio=10 tid=0x00007f56dc3c9000 nid=0x25fd
waiting on condition [0x00007f56b31dc000]
   java.lang.Thread.State: WAITING (parking)
	at sun.misc.Unsafe.park(Native Method)
	- parking to wait for  <0x00000006f4688ab0> (a java.util.concurrent.Semaphore$NonfairSync)
	at java.util.concurrent.locks.LockSupport.park(LockSupport.java:186)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:834)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedInterruptibly(AbstractQueuedSynchronizer.java:994)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireSharedInterruptibly(AbstractQueuedSynchronizer.java:1303)
	at java.util.concurrent.Semaphore.acquire(Semaphore.java:472)
	at org.apache.drill.exec.ops.SendingAccountor.waitForSendComplete(SendingAccountor.java:48)
	- locked <0x00000006f4688a78> (a org.apache.drill.exec.ops.SendingAccountor)
	at org.apache.drill.exec.ops.FragmentContext.waitForSendComplete(FragmentContext.java:486)
	at org.apache.drill.exec.physical.impl.BaseRootExec.close(BaseRootExec.java:134)
	at org.apache.drill.exec.physical.impl.ScreenCreator$ScreenRoot.close(ScreenCreator.java:141)
	at org.apache.drill.exec.work.fragment.FragmentExecutor.closeOutResources(FragmentExecutor.java:313)
	at org.apache.drill.exec.work.fragment.FragmentExecutor.cleanup(FragmentExecutor.java:155)
	at org.apache.drill.exec.work.fragment.FragmentExecutor.run(FragmentExecutor.java:264)
	at org.apache.drill.common.SelfCleaningRunnable.run(SelfCleaningRunnable.java:38)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
   Locked ownable synchronizers:	- <0x000000073f800b68> (a java.util.concurrent.ThreadPoolExecutor$Worker)
{noformat}

*Reproduce*
Ran modified ConcurrencyTest.java referenced in DRILL-4338 and cancel after 2-3 seconds. ConcurrencyTest.java
should be modified as follows:
{{ExecutorService executor = Executors.newFixedThreadPool(10);}} and execute 200 queries 
{{for (int i = 1; i <= 200; i++)}}.
Query: {{select * from dfs.`sample.json`}}, data set is attached.

*Problem description*
Looks like the problem occurs when the server has sent data to the client and waiting from
the client confirmation that data was received. In this case [{{ChannelListenerWithCoordinationId}}|https://github.com/apache/drill/blob/master/exec/rpc/src/main/java/org/apache/drill/exec/rpc/RequestIdMap.java#L118]
is used for tracking. {{ChannelListenerWithCoordinationId}} contains {{StatusHandlerListener}}
which keeps track of sent batches. It updates {{SendingAccountor}} with information about
how many batches were sent and how many batches have reached the client (successfully or not).

When sent operation is complete (successfully or not) {{operationComplete(ChannelFuture future)}}
is called. Given future contains information if sent operation was successful or not, failure
cause, channel status etc. If sent operation was successful we do nothing since in this case
client sent us acknowledgment and when we received it, we notified {{StatusHandlerListener}}
has batch was received. But if sent operation has failed, we need to notify {{StatusHandlerListener}}
was sent has unsuccessful.

{{operationComplete(ChannelFuture future)}} code:
{code}
      if (!future.isSuccess()) {
        removeFromMap(coordinationId);
        if (future.channel().isActive()) {
          throw new RpcException("Future failed");
        } else {
          setException(new ChannelClosedException());
        }
      }
    }
{code}

Method {{setException}} notifies {{StatusHandlerListener}} that batch sent has failed but
it's only called when channel is closed. When channel is still open we just throw {{RpcException}}.
This is where the problem occurs. {{operationComplete(ChannelFuture future)}} is called via
Netty {{DefaultPromise.notifyListener0}} method which catches {{Throwable}} and just logs
it. So even of we throw exception nobody is notified about it especially {{StatusHandlerListener}}.

*Fix*
Use {{setException}} even if channel is still open instead of throwing exception.

This problem was also raised in [PR-463|https://github.com/apache/drill/pull/463] but was
decided to be fixed in the scope of new Jira.







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