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https://issues.apache.org/jira/browse/HDFS-6788?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14081396#comment-14081396
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Yongjun Zhang commented on HDFS-6788:
-------------------------------------
Thanks [~andrew.wang] and [~arpitagarwal] a lot for the review!
Based on the info Arpit provided, I do see a place that need to be changed. Let
me look more thoroughly. I will address the comments from both of you in next
revision. Thanks.
> Improve synchronization in BPOfferService with read write lock
> --------------------------------------------------------------
>
> Key: HDFS-6788
> URL: https://issues.apache.org/jira/browse/HDFS-6788
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Affects Versions: 2.5.0
> Reporter: Yongjun Zhang
> Assignee: Yongjun Zhang
> Attachments: HDFS-6788.001.patch
>
>
> Threads in DN (DataXceiver, PacketResponder, Async disk worker etc) may block
> at BPOfferService.getBlockPoolId() when calling BPOfferService.checkBlock(),
> though they are just reading the same blockpool id. This is unnecessary
> overhead and may cause performance hit when many threads compete. Filing this
> jira to replace synchronized method with read write lock
> (ReentrantReadWriteLock).
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