[jira] [Created] (SPARK-10072) BlockGenerator can deadlock when the queue block queue of generate blocks fills up to capacity

["Tathagata Das (JIRA)" <ji...@apache.org>]

Tathagata Das created SPARK-10072:
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             Summary: BlockGenerator can deadlock when the queue block queue of generate blocks fills up to capacity
                 Key: SPARK-10072
                 URL: https://issues.apache.org/jira/browse/SPARK-10072
             Project: Spark
          Issue Type: Bug
          Components: Streaming
            Reporter: Tathagata Das
            Assignee: Tathagata Das


Generated blocks are inserted into an ArrayBlockingQueue, and another thread pulls stuff from the ArrayBlockingQueue and pushes it into BlockManager. Now if that queue fills up to capacity (default is 10 blocks), then the inserting into queue (done in the function updateCurrentBuffer) get blocked inside a synchronized block. However, the thread that is pulling blocks from the queue uses the same lock to check the current (active or stopped) while pulling from the queue. Since the block generating threads is blocked (as the queue is full) on the lock, this thread that is supposed to drain the queue gets blocked. Ergo, deadlock.



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