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https://issues.apache.org/jira/browse/LUCENE-4398?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael McCandless updated LUCENE-4398:
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Attachment: LUCENE-4398.patch
Patch w/ test case and fix.
The issue doesn't affect 4.x/5.x because on flush we completely clear the slate
/ allocate a new DWPT. I'll commit the test case to be sure...
I added a InvertedDocConsumerPerField.close() method, and implemented it in
TermsHashPerField to account for freeing up the RAM.
> "Memory Leak" in TermsHashPerField memory tracking
> --------------------------------------------------
>
> Key: LUCENE-4398
> URL: https://issues.apache.org/jira/browse/LUCENE-4398
> Project: Lucene - Core
> Issue Type: Bug
> Affects Versions: 3.4
> Reporter: Tim Smith
> Assignee: Michael McCandless
> Attachments: LUCENE-4398.patch
>
>
> I am witnessing an apparent leak in the memory tracking used to determine
> when a flush is necessary.
> Over time, this will result in every single document being flushed into its
> own segment as the memUsage will remain above the configured buffer size,
> causing a flush to be triggered after every add/update.
> Best I can figure, this is being caused by TermsHashPerField's tracking of
> memory usage for postingsHash and/or postingsArray combined with
> multi-threaded feeding.
> I suspect that the TermsHashPerField's postingsHash is growing in one thread,
> then, when a segment is flushed, a single, different thread will merge all
> TermsHashPerFields in FreqProxTermsWriter and then call shrinkHash(). I
> suspect this call of shrinkHash() is seeing an old postingsHash array, and
> subsequently not releasing all the memory that was allocated.
> If this is the case, I am also concerned that FreqProxTermsWriter will not
> write the correct terms into the index, although I have not confirmed that
> any indexing problem occurs as of yet.
> NOTE: i am witnessing this growth in a test by subtracting the amount or
> memory allocated (but in a "free" state) by
> perDocAllocator/byteBlockAllocator/charBlocks/intBlocks from
> DocumentsWriter.memUsage.get() in IndexWriter.doAfterFlush()
> I will see this stay at a stable point for a while, then on some flushes, i
> will see this grow by a couple of bytes, and all subsequent flushes will
> never go back down the the previous state
> I will continue to investigate and post any additional findings
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