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https://issues.apache.org/jira/browse/HBASE-16440?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Anoop Sam John updated HBASE-16440:
-----------------------------------
Attachment: HBASE-16440_V2.patch
Addressed comments from Stack.
Added a test. With out the patch it some times fails as we will keep more than
the maxCount #chunks in the pool!
Thanks for the review stack.
> MemstoreChunkPool might cross its maxCount of chunks to pool
> ------------------------------------------------------------
>
> Key: HBASE-16440
> URL: https://issues.apache.org/jira/browse/HBASE-16440
> Project: HBase
> Issue Type: Sub-task
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Fix For: 2.0.0
>
> Attachments: HBASE-16440.patch, HBASE-16440_V2.patch
>
>
> {code}
> void putbackChunks(BlockingQueue<Chunk> chunks) {
> int maxNumToPutback = this.maxCount - reclaimedChunks.size();
> if (maxNumToPutback <= 0) {
> return;
> }
> chunks.drainTo(reclaimedChunks, maxNumToPutback);
> // clear reference of any non-reclaimable chunks
> if (chunks.size() > 0) {
> if (LOG.isTraceEnabled()) {
> LOG.trace("Left " + chunks.size() + " unreclaimable chunks, removing
> them from queue");
> }
> chunks.clear();
> }
> }
> {code}
> There is no synchroization. 2 threads might be calling this API as part of a
> MSLAB close. (Once the memstore is flushed). It pass all the chunks used by
> it. (Those might not have been come from pool also). We try to put back
> chunks such that it is not crossing maxCount. Suppose maxCount is 10 and
> currently no chunks in 'reclaimedChunks'. Say both threads at line one. Both
> see 'maxNumToPutback ' as 10 and that will make 20 chunks being pooled.
> Similar issue is in putbackChunk(Chunk chunk) API also.
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