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https://issues.apache.org/jira/browse/SOLR-13963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16980860#comment-16980860
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Colvin Cowie commented on SOLR-13963:
-------------------------------------
I've attached a patch that fixes it, and I've included a new test that
reproduces the problem without the fix...
I don't know enough about the way the tests have been done for Solr to know
what the best way to write a test for this is, so I've just done something that
worked.
But if there is a better way to do it / different coding style etc, then
obviously I'm open to it being done differently.
> JavaBinCodec has concurrent modification of CharrArr resulting in corrupt
> intranode updates
> -------------------------------------------------------------------------------------------
>
> Key: SOLR-13963
> URL: https://issues.apache.org/jira/browse/SOLR-13963
> Project: Solr
> Issue Type: Bug
> Security Level: Public(Default Security Level. Issues are Public)
> Affects Versions: 8.3
> Reporter: Colvin Cowie
> Priority: Major
> Attachments: SOLR-13963.patch
>
>
> Discussed on the mailing list "Possible data corruption in JavaBinCodec in
> Solr 8.3 during distributed update?"
>
> In summary, after moving to 8.3 we had a consistent (but non-deterministic)
> set of failing tests where the data being sent in intranode requests was
> _sometimes_ corrupted. For example if the well formed data was
> _'fieldName':"this is a long string"_
> The error we saw from Solr might be that
> unknown field _+'fieldNamis a long string"+_
>
> The change that indirectly caused to this issue to materialize was from
> SOLR-13682 which meant that
> org.apache.solr.common.SolrInputDocument.writeMap(EntryWriter) would call
> org.apache.solr.common.SolrInputField.getValue() rather than
> org.apache.solr.common.SolrInputField.getRawValue() as it had before.
>
> getRawValue for a string calls
> org.apache.solr.common.util.ByteArrayUtf8CharSequence._getStr() which in this
> context calls
> org.apache.solr.common.util.JavaBinCodec.getStringProvider()
>
> JavaBinCodec has a CharArr, _arr_, which is modified in two different
> locations, but only one of which is protected with a synchronized block
>
> getStringProvider() synchronizes on _arr_:
>
> [https://github.com/apache/lucene-solr/blob/master/solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java#L966]
>
> but _readStr() doesn't:
>
> [https://github.com/apache/lucene-solr/blob/master/solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java#L930]
>
> The two methods are called concurrently, but wheren't prior to SOLR-13682.
>
> Adding a synchronized block into _readStr() around the modification of _arr_
> fixes the problem as far as I can see.
>
> Also, the problem does not seem to occur when using the dynamic schema mode
> of autoCreateFields=true in the updateRequestProcessorChain.
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