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https://issues.apache.org/jira/browse/HBASE-11492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14058919#comment-14058919
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Nicolas Liochon commented on HBASE-11492:
-----------------------------------------
hold on.
The issue is real, but it's not java. I fucked up the test.
The issue is that we're taking the value from ipc.server.tcpnodelay, and this
is set in the default hadoop conf that we're getting from the classpath in
hadoop-common
It's much less fun, but simpler to understand. We still need to fix this
however. What about renaming it to hbase.ipc.server.tcpnodelay and say we're
done?
> 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, 0.94.22
>
> Attachments: 11492.v1.patch, 11492.v1.withp1.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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