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From "Yu Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-17747) Support both weak and soft object pool
Date Wed, 08 Mar 2017 08:00:47 GMT

    [ https://issues.apache.org/jira/browse/HBASE-17747?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15900879#comment-15900879

Yu Li commented on HBASE-17747:

bq. So in normal mode (not embedded) how the perf of read from BC looks like? U see any change?
Let's be cautious here and will do some comparison test through YCSB and upload the result
here later.

The patch v2 could not apply to latest code base, will rebase later.

> 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, HBASE-17747.v2.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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