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https://issues.apache.org/jira/browse/HBASE-17747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15900759#comment-15900759
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Anoop Sam John commented on HBASE-17747:
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So here there is no change in usage of soft ref instead of weak.. Just you
doing the abstraction and giving both impls so as to make a way for the
embedded mode usage. Fine. +1
> Support both weak and soft object pool
> --------------------------------------
>
> Key: HBASE-17747
> URL: https://issues.apache.org/jira/browse/HBASE-17747
> Project: HBase
> Issue Type: Improvement
> Reporter: Yu Li
> Assignee: Yu Li
> Attachments: HBASE-17747.patch
>
>
> During YCSB testing on embedded mode after HBASE-17744, we found that under
> high read load GC is quite severe even with offheap L2 cache. After some
> investigation, we found it's caused by using weak reference for
> IdReadWriteLock. In embedded mode the read is so quick that the lock might
> already get promoted to the old generation when the weak reference is
> cleared, which causes dirty card table thus slowing YGC.
> So we proposed to use soft reference for this IdReadWriteLock used in cache,
> which won't get cleared until JVM memory is not enough, and could resolve the
> issue mentioned above. What's more, we propose to extend the WeakObjectPool
> to be more generate to support both weak and soft reference.
> Note that this issue only emerges under embedded mode with DirectOperator, in
> which case all costs on the wire is removed thus produces extremely high
> workloads.
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