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https://issues.apache.org/jira/browse/HBASE-22422?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16846518#comment-16846518
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Zheng Hu commented on HBASE-22422:
----------------------------------
The bug never happened since applied debug3.patch, it's some frustrating.
Discussed with [~Apache9], it's possible that the stack track catcher make the
release a bit slow and the concurrent bug disappear.
{code}
+ @Override
+ public boolean release() {
+ callerSet.add(debugString(Thread.currentThread().getStackTrace(),
this.refCnt()));
+ return super.release();
+ }
{code}
So I plan to pass the caller's string message as an argument into release,
then it won't cost that much time as the strace trace do.... at the same time,
will continue to check those code paths.
> Retain an ByteBuff with refCnt=0 when getBlock from LRUCache
> ------------------------------------------------------------
>
> Key: HBASE-22422
> URL: https://issues.apache.org/jira/browse/HBASE-22422
> Project: HBase
> Issue Type: Sub-task
> Components: BlockCache
> Reporter: Zheng Hu
> Assignee: Zheng Hu
> Priority: Major
> Attachments: 0001-debug2.patch, 0001-debug2.patch, 0001-debug2.patch,
> 0001-debug3.patch, HBASE-22422.HBASE-21879.v01.patch,
> LRUBlockCache-getBlock.png, debug.patch,
> failed-to-check-positive-on-web-ui.png, image-2019-05-15-12-00-03-641.png
>
>
> After runing YCSB scan/get benchmark in our XiaoMi cluster, we found the get
> QPS dropped from 25000/s to hunderds per second in a cluster with five
> nodes.
> After enable the debug log at YCSB client side, I found the following
> stacktrace , see
> https://issues.apache.org/jira/secure/attachment/12968745/image-2019-05-15-12-00-03-641.png.
>
> After looking into the stractrace, I can ensure that the zero refCnt block is
> an intermedia index block, see [2] http://hbase.apache.org/images/hfilev2.png
> Need a patch to fix this.
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