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https://issues.apache.org/jira/browse/OOZIE-3263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16492826#comment-16492826
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Peter Bacsko commented on OOZIE-3263:
-------------------------------------
I have a theory for this.
1. Thread#1 reaches end of the sequence (5000) and enters {{resetSequence()}}
2. Thread#2 also reaches the end of the sequence and enterd {{resetSequence()}}
too
3. Thread#1 successfully acquires ZK lock and begins to perform resetting the
distributed counter
4. Thread#2 tries to acquire the ZK lock in a loop but fails after multiple
attempts.
5. An exception is thrown from {{resetSequence()}} which is caught by
{{createSequence()}} and calls {{UUIDService.getCounter()}} as a fallback
mechanism, which returns 0.
6. In the meantime, Thread #1 has returned 0 and the respective
{{AtomicInteger}} has been incremented
7. Thread#2 also increments {{AtomicInteger}} at position 0 in the array
Step #4 seems to be highly unlikely. Lock timeout for ZK is 5 seconds and there
are 3 attempts to acquire the lock. Even on a slow computer, it shouldn't take
15 seconds, it sounds unacceptably slow.
Regardless, we need more logs to find out if this sequence of events causes the
test error.
> Flaky test TestZKUUIDService#testResetSequence_withMultiThread
> --------------------------------------------------------------
>
> Key: OOZIE-3263
> URL: https://issues.apache.org/jira/browse/OOZIE-3263
> Project: Oozie
> Issue Type: Sub-task
> Reporter: Peter Bacsko
> Assignee: Peter Bacsko
> Priority: Major
>
> The test case {{testResetSequence_withMultiThread}} failed with the following
> error:
> {noformat}
> junit.framework.AssertionFailedError: expected:<3> but was:<2>
> at junit.framework.Assert.fail(Assert.java:57)
> at junit.framework.Assert.failNotEquals(Assert.java:329)
> at junit.framework.Assert.assertEquals(Assert.java:78)
> at junit.framework.Assert.assertEquals(Assert.java:234)
> at junit.framework.Assert.assertEquals(Assert.java:241)
> at junit.framework.TestCase.assertEquals(TestCase.java:409)
> at
> org.apache.oozie.service.TestZKUUIDService.testResetSequence_withMultiThread(TestZKUUIDService.java:214)
> {noformat}
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