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https://issues.apache.org/jira/browse/SOLR-16992?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17768131#comment-17768131
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Alex Deparvu commented on SOLR-16992:
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hmm, I think I'm leaning more towards option number 1:
bq. wait for every Future, aggregated the results (and or throw an aggregated
exceptions), then shutdown
{quote}I don't really understand your response (particularly given your
responses to my later ideas) so i'm suspicious that i was vague to the point of
confusing you.
what i'm suggesting is that if this sequence of code happens...
{quote}
ah yes thank you for clarifying. now it makes more sense and I agree with this
being useful.
bq. Even if we re-wrote StreamOpener to look something like this, there would
still be a concurrency race condition...
yes, I fully agree the race would still be there. I was proposing a best effort
early termination to avoid having that exception in the logs. the alternative
being: it calls open, the internal state check triggers an exception, it needs
to bubble up and be handled on the parent close method.
the way I see it is a simple shortcut in the StreamOpener: `isClosed ? return
null;`
bq. checking "isClosed ?" really needs to happen internally to the logic in the
TupleStream instances, and it either needs to happen in blocks syncrhonized by
the same gate, or using a private volatile boolean isClosed
I agree with all of this.
I think there is another case we need to look at in the TupleStream#getReplicas
where the cache close would not get called in case of an exception.
are you already working on a patch for this or can I give it a go?
> 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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