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https://issues.apache.org/jira/browse/HADOOP-7105?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13473120#comment-13473120
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luoli commented on HADOOP-7105:
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hi longjing ge,I am a little confused...
What is the synchronized in Reader suppose to do original?
If it is to protect the readSelector, then the patch can't protect it any more.
if not, why don't just remove the synchronized in registerChannel?
> [IPC] Improvement of lock mechanism in Listener and Reader thread
> -----------------------------------------------------------------
>
> Key: HADOOP-7105
> URL: https://issues.apache.org/jira/browse/HADOOP-7105
> Project: Hadoop Common
> Issue Type: Improvement
> Components: ipc
> Affects Versions: 0.21.0
> Reporter: jinglong.liujl
> Attachments: improveListenerLock2.patch, improveListenerLock.patch
>
>
> In many client cocurrent access, single thread Listener will become
> bottleneck. Many client can't be served, and get connection time out.
> To improve Listener capacity, we make 2 modification.
> 1. Tuning ipc.server.listen.queue.size to a larger value to avoid client
> retry.
> 2. In currently implement, Listener will call registerChannel(), and
> finishAdd() in Reader, which will request Reader synchronized lock. Listener
> will cost too many time in waiting for this lock.
> We have made test,
> ./bin/hadoop org.apache.hadoop.hdfs.NNThroughputBenchmark -op create
> -threads 10000 -files 10000
> case 1 : Currently
> can not pass. and report
> hadoop-rd101.jx.baidu.com/10.65.25.166:59310. Already tried 0 time(s).
> case 2 : tuning back log to 10240
> average cost : 1285.72 ms
> case 3 : tuning back log to 10240 , and improve lock mechanism in patch
> average cost : 941.32 ms
> performance in average cost will improve 26%
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