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  1. Spark
  2. SPARK-12049

User JVM shutdown hook can cause deadlock at shutdown

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 1.5.2, 1.6.0
    • Fix Version/s: 1.5.3, 1.6.0
    • Component/s: Spark Core
    • Labels:
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    • Target Version/s:

      Description

      Here's a simplification of a deadlock that can occur a shutdown if the user app has also installed a shutdown hook to clean up:

      • Spark Shutdown Hook thread runs
      • SparkShutdownHookManager.runAll() is invoked, locking SparkShutdownHookManager as it is synchronized
      • A user shutdown hook thread runs
      • User hook tries to call, for example StreamingContext.stop(), which is synchronized and locks it
      • User hook blocks when the StreamingContext tries to remove() the Spark Streaming shutdown task, since it's synchronized per above
      • Spark Shutdown Hook tries to execute the Spark Streaming shutdown task, but blocks on StreamingContext.stop()

      I think this is actually not that critical, since it requires a pretty specific setup, and I think it can be worked around in many cases by integrating with Hadoop's shutdown hook mechanism like Spark does so that these happen serially.

      I also think it's solvable in the code by not locking SparkShutdownHookManager in the 3 methods that are synchronized since these are really only protecting hooks. runAll() shouldn't hold the lock while executing hooks.

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            • Assignee:
              srowen Sean R. Owen
              Reporter:
              srowen Sean R. Owen
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                Updated:
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