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https://issues.apache.org/jira/browse/HDFS-5790?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13887213#comment-13887213
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Suresh Srinivas commented on HDFS-5790:
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I know that many of the HDFS restarts with running jobs that have opened many
files run into this issue. In the past I had fixed a bug where namenode did
editlog sync holding lock. Even with that I see that this issue slows down
lease recovery and namenode in such restarts becomes unresponsive. That said, I
am okay not putting this into 2.3.
> LeaseManager.findPath is very slow when many leases need recovery
> -----------------------------------------------------------------
>
> Key: HDFS-5790
> URL: https://issues.apache.org/jira/browse/HDFS-5790
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode, performance
> Affects Versions: 2.3.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: 3.0.0, 2.4.0
>
> Attachments: hdfs-5790.txt, hdfs-5790.txt
>
>
> We recently saw an issue where the NN restarted while tens of thousands of
> files were open. The NN then ended up spending multiple seconds for each
> commitBlockSynchronization() call, spending most of its time inside
> LeaseManager.findPath(). findPath currently works by looping over all files
> held for a given writer, and traversing the filesystem for each one. This
> takes way too long when tens of thousands of files are open by a single
> writer.
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