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https://issues.apache.org/jira/browse/HBASE-11492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14058307#comment-14058307
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Liang Xie commented on HBASE-11492:
-----------------------------------
I have no more knowledge on this area, but i could not convince me to believe
the original "socket().setTcpNoDelay" style did not take effect, since HDFS +
HBase always use this style, right? so weird, my god...
> The servers do not honor the tcpNoDelay option
> ----------------------------------------------
>
> Key: HBASE-11492
> URL: https://issues.apache.org/jira/browse/HBASE-11492
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 0.92.2, 0.98.0, 0.96.0, 0.99.0, 0.94.20
> Reporter: Nicolas Liochon
> Assignee: Nicolas Liochon
> Priority: Critical
> Fix For: 0.99.0, 0.98.5
>
> Attachments: 11492.v1.patch
>
>
> There is an option to set tcpNoDelay, defaulted to true, but the socket
> channel is actually not changed. As a consequence, the server works with
> nagle enabled. This leads to very degraded behavior when a single connection
> is shared between threads. We enter into conflicts with nagle and tcp delayed
> ack.
> Here is an example of performance with the PE tool plus HBASE-11491:
> {noformat}
> oneCon #client sleep exeTime (seconds)
> avg latency, sleep excluded (microseconds)
> true 1 0 31
> 310
> false 1 0 31
> 310
> true 2 0 50
> 500
> false 2 0 31
> 310
> true 2 5 488 (including 200s sleeping)
> 2880
> false 2 5 246 (including 200s sleeping)
> 460
> {noformat}
> The latency is multiple by 5 (2880 vs 460) when the connection is shared.
> This is the delayed ack kicking in. This can be fixed by really using tcp no
> delay.
> Any application sharing the tcp connection between threads has the issue.
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