[DRILL-5599] Notify StatusHandlerListener that batch sending has failed even if channel is still open

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.11.0
• Fix Version/s: 1.11.0
• Labels: ready-to-commit
• Assignee: Arina Ielchiieva
• Reporter: Arina Ielchiieva
• Reviewer: Padma Penumarthy
• Created: 20/Jun/17 11:35
• Updated: 03/Aug/17 17:53
• Resolved: 26/Jun/17 09:05

Description

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.

"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)

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 is used for tracking. ChannelListenerWithCoordinationId contains StatusHandler 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 that batch was received. But if sent operation has failed, we need to notify StatusHandler that sent was unsuccessful.

operationComplete(ChannelFuture future) code:

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

Method setException notifies StatusHandler 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 StatusHandler.

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

This problem was also raised in PR-463 but was decided to be fixed in the scope of new Jira.

Issue Links

• is duplicated by: DRILL-3665 Deadlock while executing CTAS that runs out of memory
• relates to: DRILL-4296 Query hangs in CANCELLATION_REQUESTED when cancelled after it starts returning results
• relates to: DRILL-3241 Query with window function runs out of direct memory and does not report back to client that it did
• relates to: DRILL-3119 Query stays in "CANCELLATION_REQUESTED" status in UI after OOM of Direct buffer memory
• relates to: DRILL-4338 Concurrent query remains in CANCELLATION_REQUESTED state
• relates to: DRILL-4595 FragmentExecutor.fail() should interrupt the fragment thread to avoid possible query hangs
• links to: GitHub Pull Request #857