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https://issues.apache.org/jira/browse/SOLR-16992?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17768953#comment-17768953
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Chris M. Hostetter commented on SOLR-16992:
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{quote}it feels like adding a closed flag to all tule stream impls would
introduce a large amount of changes. I am thinking it could be done as a future
improvement.
{quote}
yeah, sure – totally fair game to open that as a distinct jira/PR
(arguably the SolrClientCache changes could/should be a distinct jira from the
{{Future}} handling as well)
{quote}pushed an early PR...
{quote}
General impressions:
* I like the impl of {{SolrClientCache.close()}} a lot ... strictly speaking i
don't think {{AtomicBoolean}} is actually necessary given that (all?) the
methods are synchronized, but i don't care. i prefer your AtomicBoolean
approach over depending on the synchronization (maybe/hopefully enough of the
methods can similarly be improved to the point we can remove the
synchronization some day)
* {{checkState();}} is too vague of a method name to be readable in context
w/o consulting javados. The convention in lucene is {{ensureOpen(); }} which i
think is really self documenting as you skim code
* I think having a
{{StreamExecutorHelper.submitAllAndAwaitAggregatingExceptions(...)}} method
that is re-used in multiple streams is a fine idea, but I think the "guts" of
it should be re-implemented as an {{ExecutorUtil}} class that takes an existing
{{ExecutorService}} as an argument (and does not close it even on exception)
** but the {{if (result != null) ...}} logic should not be part of a general
{{ExecutorUtil}} helper
** arguably it shouldn't be part of
{{StreamExecutorHelper.submitAllAndAwaitAggregatingExceptions(...)}} either ...
i'm pretty sure if you check the diffs of all the methods where you are using
it in your PR not all of them currently ignore {{null}} results.
> 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
> Assignee: Alex Deparvu
> Priority: Major
> Attachments:
> OUTPUT-org.apache.solr.client.solrj.io.stream.StreamingTest.txt,
> thetaphi_solr_Solr-main-Linux_14679.log.txt
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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