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https://issues.apache.org/jira/browse/METRON-728?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15880881#comment-15880881
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ASF GitHub Bot commented on METRON-728:
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Github user cestella commented on the issue:
https://github.com/apache/incubator-metron/pull/463
Yeah, I can get behind that, @justinleet I'd state it slightly differently
though. It's not that we want to test the Stream so much as we want to test
that the Spliterator, when interacting with a stream, makes the right number of
splits. That was the core problem with `Files.lines()` was that it made one
split, not many splits.
What we really want to test here is that the spliterator splits the
expected number of times. What we have indirectly tests that, but it relies on
the ForkPool to work in a consistent way, which isn't going to happen. Anyway,
I pushed a commit, see how you like it.
> ReaderSpliteratorTest fails randomly and extremely rarely
> ---------------------------------------------------------
>
> Key: METRON-728
> URL: https://issues.apache.org/jira/browse/METRON-728
> Project: Metron
> Issue Type: Bug
> Affects Versions: 0.3.1
> Reporter: Justin Leet
> Assignee: Justin Leet
>
> See logs at
> https://travis-ci.org/justinleet/incubator-metron/builds/203298348
> I was able to reproduce this locally by calling
> {{testActuallyParallel_mediumBatch}} in a {{while(true)}} loop. It can also
> occur in {{testActuallyParallel_mediumBatchImplicitlyParallel()}}. I also
> had to add
> {{forkJoinPool.shutdownNow();}} to the end of the test, because otherwise OOM
> errors occur.
> My current assumption is that there's no guarantee you ever actually end up
> running in parallel, so in extremely rare cases you just end up running one
> thread.
> I've had it vary wildly when I hit it, from within a second or two to running
> for over a minute before an assertion failure occurs.
> We could just alter the assertion to be
> {code}Assert.assertTrue(threads.size() <= (int) Math.ceil(9.0 / 2) &&
> threads.size() >= 1);{code}
> This defeats the purpose of testing the parallelism a bit, but if there's no
> guarantee we actually get parallelism there's not a fantastic way to test it.
> Given the extreme rarity, we might want to just live with the fact that
> occasionally {{threads.size() >= 1}} hits the threads.size() == 1 case on the
> two tests.
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