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Posted to hdfs-dev@hadoop.apache.org by "Zhe Zhang (JIRA)" <ji...@apache.org> on 2017/04/27 16:43:05 UTC
[jira] [Reopened] (HDFS-8873) Allow the directoryScanner to be
rate-limited
[ https://issues.apache.org/jira/browse/HDFS-8873?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Zhe Zhang reopened HDFS-8873:
-----------------------------
> Allow the directoryScanner to be rate-limited
> ---------------------------------------------
>
> Key: HDFS-8873
> URL: https://issues.apache.org/jira/browse/HDFS-8873
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Affects Versions: 2.7.1
> Reporter: Nathan Roberts
> Assignee: Daniel Templeton
> Labels: 2.7.2-candidate
> Fix For: 2.8.0, 3.0.0-alpha1
>
> Attachments: HDFS-8873.001.patch, HDFS-8873.002.patch, HDFS-8873.003.patch, HDFS-8873.004.patch, HDFS-8873.005.patch, HDFS-8873.006.patch, HDFS-8873.007.patch, HDFS-8873.008.patch, HDFS-8873.009.patch, HDFS-8873-branch-2.7.009.patch
>
>
> The new 2-level directory layout can make directory scans expensive in terms of disk seeks (see HDFS-8791) for details.
> It would be good if the directoryScanner() had a configurable duty cycle that would reduce its impact on disk performance (much like the approach in HDFS-8617).
> Without such a throttle, disks can go 100% busy for many minutes at a time (assuming the common case of all inodes in cache but no directory blocks cached, 64K seeks are required for full directory listing which translates to 655 seconds)
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