[jira] [Created] (IMPALA-9611) Hang in HandoffToProbesAndWait()

["Tim Armstrong (Jira)" <ji...@apache.org>]

Tim Armstrong created IMPALA-9611:
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             Summary: Hang in HandoffToProbesAndWait()
                 Key: IMPALA-9611
                 URL: https://issues.apache.org/jira/browse/IMPALA-9611
             Project: IMPALA
          Issue Type: Bug
          Components: Backend
    Affects Versions: Impala 3.4.0
            Reporter: Tim Armstrong
            Assignee: Tim Armstrong


I saw a hang triggered by test_failpoints in JoinBuilder::HandofftoProbesAndWait(), where the thread was blocked but build_side_state->is_cancelled_ is true.

The sequence of events leading to the bug is as follows:
 * Thread A is in HandoffToProbesAndWait(), reads is_cancelled_ and sees false.
 * Thread B in RuntimeState::Cancel() sets is_cancelled_ = true, acquires cancellation_cvs_lock_, then calls NotifyAll() on the condition variable
 * Thread A calls Wait() on the cv, blocks forever.

I think this is most likely if thread A is de-scheduled at the wrong time.



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