[jira] [Commented] (TEZ-3695) TestTezSharedExecutor fails sporadically

["Jason Lowe (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-3695?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15981184#comment-15981184 ] 

Jason Lowe commented on TEZ-3695:
---------------------------------

Looks like the test has an inherent race in it:
{code}
    List<Integer> list = new ArrayList<>();
    Future<?> f1 = service.submit(new Wait(list));
    List<Future<?>> futures = new ArrayList<>();
    for (int i = 0; i < 10; ++i) {
      futures.add(service.submit(new Appender<Integer>(list, i)));
    }

    // This shutdown does not prevent already submitted tasks from completing.
    service.shutdown();

    // Until we notify nothing moves forward.
    Assert.assertEquals(0, list.size());
    _notify(list);
    f1.get();
{code}

The code assumes that the executor will be fast enough to get to the {{wait}} in the {{Wait}} code before the main test code tries to do the {{notify}} to wake it up.  However if the executor is a little slower then the main code will trigger the {{notify}} _before_ any code is waiting and then we end up with an indefinite wait and test timeout.

The test should be using something like a {{CountdownLatch}} to coordinate between the {{Wait}} code and main test code.

> TestTezSharedExecutor fails sporadically
> ----------------------------------------
>
>                 Key: TEZ-3695
>                 URL: https://issues.apache.org/jira/browse/TEZ-3695
>             Project: Apache Tez
>          Issue Type: Bug
>            Reporter: Jason Lowe
>
> TestTezSharedExecutor#testSerialExecution is timing out more often than not for me when running the full TezTezSharedExecutor test suite.



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