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https://issues.apache.org/jira/browse/SOLR-16992?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17768085#comment-17768085
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Alex Deparvu commented on SOLR-16992:
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I agree with your analysis. makes perfect sense to me.
given the proliferation of this pattern across multiple classes, does it make
sense to move this to a common util class and call it everywhere? not sure if
possible but it would help nail it down once for all cases.
re. `I think at a minimum, CloudSolrStream.openStreams() should be changed such
that...`
> It waits for the results of every Future, even if one of them throws an
> exception
> it might make sense to instead use shutdownNow() + awaitTermination() if/when
> any Future fails
it feels like there is some overlap between these 2 ideas. not sure how the
impls would vary but I like waiting for everything to finish and discarding any
useless results (prioritize the exception).
re. `Going above and beyond that, it's worth considering:`
> Change SolrClientCache so that any method that will add to solrClients throws
> an IllegalStateException if isClosed
-0 it doesn't feel like this class is a correct place to tackle this.
> make all TupleStream instances throw an IllegalStateException from open()
> and/or read() if isClosed
+1 I like this option the most. this would prevent any bad patterns from
escaping and fail in a clearer way in the test?
I think it can be legal to call close twice (treat it as an idempotent
operation), but not open after close that feels like a strong breach of api
contract.
Another idea can we shortcut `StreamOpener` to bail early if stream is closed?
so we avoid some noise in the logs.
> Non-reproducible StreamingTest failures -- suggests CloudSolrStream
> concurency race condition
> ---------------------------------------------------------------------------------------------
>
> Key: SOLR-16992
> URL: https://issues.apache.org/jira/browse/SOLR-16992
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Reporter: Chris M. Hostetter
> Priority: Major
> Attachments:
> OUTPUT-org.apache.solr.client.solrj.io.stream.StreamingTest.txt,
> thetaphi_solr_Solr-main-Linux_14679.log.txt
>
>
> Roughly 3% of all jenkins jobs that run {{StreamingTest}} wind up having
> suite level failures.
> These failures have historically taken the form of
> {{com.carrotsearch.randomizedtesting.ThreadLeakError}} and the leaked threads
> all have names like
> {{"h2sc-718-thread-2"}} indicating that they come from the internal
> {{ExecutorService}} of an {{{}Http2SolrClient{}}}.
> In my experience, the seeds from these failures have never reproduced -
> suggesting that the problem is related to concurrency.
> SOLR-16983 restored the (correct) use of {{ObjectReleaseTracker}} which in
> theory should help pinpoint where {{Http2SolrClient}} instances might not be
> getting closed (by causing {{ObjectReleaseTracker}} to fail with stacktraces
> of when/where any unclosed instances were created - ie: which test method)
> In practice, I have managed to force one failure from {{StreamingTest}} since
> the SOLR-16983 changes (logs to be attached soon) - but it still didn't
> indicate any leaked/unclosed {{Http2SolrClient}} instances. What it instead
> indicated was a _single_ unclosed {{InputStream}} instance related to
> {{Http2SolrClient}} connections (SOLR-16983 also added better tracking of
> this) coming from {{StreamingTest.testExceptionStream}} - a test method that
> opens _five_ very similar {{ExceptionStream}} instances, wrapping
> {{CloudSolrStream}} instance, which expect to trigger server side errors.
> By it's very design, {{ExceptionStream}} catches & records any exceptions
> from the stream it wraps, so even in the event of these "expected" server
> side errors, {{ExceptionStream.close()}} should still be correctly getting
> called (and propagating down to the {{CloudStream}} it wraps).
> I believe the underlying problem has to do with a concurrency race condition
> between the call to {{CloudStream.close()}} and the {{ExecutorService}} used
> internally by {{CloudSolrStream.openStreams()}} (details to follow)
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