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https://issues.apache.org/jira/browse/HDFS-15719?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17298434#comment-17298434
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Wei-Chiu Chuang commented on HDFS-15719:
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I'm inclined for longer timeout now.
It was initially set to 1s to make KMS client expire connections quickly, so
that it doesn't accumulate too many connections. However, more recently we
realized the entire issue was caused by jetty client that doesn't reuse
connections.
HADOOP-15813 changes the jetty client behavior so that KMS client reuses
connections. The longer timeout value should work (better) now.
> [Hadoop 3] Both NameNodes can crash simultaneously due to the short JN socket
> timeout
> -------------------------------------------------------------------------------------
>
> Key: HDFS-15719
> URL: https://issues.apache.org/jira/browse/HDFS-15719
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 3.0.0
> Reporter: Wei-Chiu Chuang
> Assignee: Wei-Chiu Chuang
> Priority: Critical
> Labels: pull-request-available
> Fix For: 3.3.1, 3.4.0, 3.1.5, 3.2.3
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> After Hadoop 3, we migrated Jetty 6 to Jetty 9. It was implemented in
> HADOOP-10075.
> However, HADOOP-10075 erroneously set the HttpServer2 socket idle timeout too
> low.
> We replaced SelectChannelConnector.setLowResourceMaxIdleTime() with
> ServerConnector.setIdleTimeout() but they aren't the same.
> Essentially, the HttpServer2's idle timeout was the default timeout set by
> Jetty 6, which is 200 seconds. After Hadoop 3, the idle timeout is set to 10
> seconds, which is unreasonable for JN. If NameNodes try to download a big
> edit log from JournalNodes (say a few hundred MB), it is likely to exceed 10
> seconds. When it happens, both NN crashes and there's no way to workaround
> unless you apply the patch in HADOOP-15696 to add a config switch for the
> idle timeout. Fortunately, it doesn't happen a lot.
> Propose: bump the idle timeout default to 200 seconds to match the behavior
> in Jetty 6. (Jetty 9 reduces the default idle timeout to 30 seconds, which is
> not suitable for JN)
> Other things to consider:
> 1. fsck serverlet? (somehow I suspect this is related to the socket timeout
> reported in HDFS-7175)
> 2. webhdfs, httpfs? --> we've also received reports that webhdfs can timeout.
> so having a longer timeout makes sense here.
> 2. kms? will the longer timeout cause more lingering sockets?
> Thanks [~zhenshan.wen] for the discussion.
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