[jira] [Created] (SPARK-14930) Race condition in CheckpointWriter.stop()

["Josh Rosen (JIRA)" <ji...@apache.org>]

Josh Rosen created SPARK-14930:
----------------------------------

             Summary: Race condition in CheckpointWriter.stop()
                 Key: SPARK-14930
                 URL: https://issues.apache.org/jira/browse/SPARK-14930
             Project: Spark
          Issue Type: Bug
          Components: Streaming
            Reporter: Josh Rosen
            Assignee: Josh Rosen


{{CheckpointWriter.stop()}} is prone to a race condition where the writer thread becomes blocked by the stop caller when trying to access the {{fs}}:

{code}
"pool-31-thread-1" #156 prio=5 os_prio=31 tid=0x00007fea02cd2000 nid=0x5c0b waiting for monitor entry [0x000000013bc4c000]
   java.lang.Thread.State: BLOCKED (on object monitor)
    at org.apache.spark.streaming.CheckpointWriter.org$apache$spark$streaming$CheckpointWriter$$fs(Checkpoint.scala:302)
    - waiting to lock <0x00000007bf53ee78> (a org.apache.spark.streaming.CheckpointWriter)
    at org.apache.spark.streaming.CheckpointWriter$CheckpointWriteHandler.run(Checkpoint.scala:224)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)

"pool-1-thread-1-ScalaTest-running-MapWithStateSuite" #11 prio=5 os_prio=31 tid=0x00007fe9ff879800 nid=0x5703 waiting on condition [0x000000012e54c000]
   java.lang.Thread.State: TIMED_WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000007bf564568> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
    at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:215)
    at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2078)
    at java.util.concurrent.ThreadPoolExecutor.awaitTermination(ThreadPoolExecutor.java:1465)
    at org.apache.spark.streaming.CheckpointWriter.stop(Checkpoint.scala:291)
    - locked <0x00000007bf53ee78> (a org.apache.spark.streaming.CheckpointWriter)
    at org.apache.spark.streaming.scheduler.JobGenerator.stop(JobGenerator.scala:159)
    - locked <0x00000007bf53ea90> (a org.apache.spark.streaming.scheduler.JobGenerator)
    at org.apache.spark.streaming.scheduler.JobScheduler.stop(JobScheduler.scala:115)
    - locked <0x00000007bf53d3f0> (a org.apache.spark.streaming.scheduler.JobScheduler)
    at org.apache.spark.streaming.StreamingContext$$anonfun$stop$1.apply$mcV$sp(StreamingContext.scala:680)
    at org.apache.spark.util.Utils$.tryLogNonFatalError(Utils.scala:1219)
    at org.apache.spark.streaming.StreamingContext.stop(StreamingContext.scala:679)
    - locked <0x00000007bf516a70> (a org.apache.spark.streaming.StreamingContext)
    at org.apache.spark.streaming.StreamingContext.stop(StreamingContext.scala:644)
    - locked <0x00000007bf516a70> (a org.apache.spark.streaming.StreamingContext)
    at org.apache.spark.streaming.MapWithStateSuite.org$apache$spark$streaming$MapWithStateSuite$$getOperationOutput(MapWithStateSuite.scala:570)
    at org.apache.spark.streaming.MapWithStateSuite.org$apache$spark$streaming$MapWithStateSuite$$testOperation(MapWithStateSuite.scala:539)
    at org.apache.spark.streaming.MapWithStateSuite$$anonfun$18.apply$mcV$sp(MapWithStateSuite.scala:407)
    at org.apache.spark.streaming.MapWithStateSuite$$anonfun$18.apply(MapWithStateSuite.scala:359)
    at org.apache.spark.streaming.MapWithStateSuite$$anonfun$18.apply(MapWithStateSuite.scala:359)
    [...]
{code}

This leads to test flakiness (SPARK-13693) and significantly slows down tests (it makes MapWithStateSuite 10 times slower). We should fix this by refactoring the code to remove unnecessary synchronization.



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