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https://issues.apache.org/jira/browse/HDFS-8046?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487252#comment-14487252
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Hudson commented on HDFS-8046:
------------------------------
SUCCESS: Integrated in Hadoop-Yarn-trunk #892 (See
[https://builds.apache.org/job/Hadoop-Yarn-trunk/892/])
HDFS-8046. Allow better control of getContentSummary. Contributed by Kihwal
Lee. (kihwal: rev 285b31e75e51ec8e3a796c2cb0208739368ca9b8)
* hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
*
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
*
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ContentSummaryComputationContext.java
*
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
> Allow better control of getContentSummary
> -----------------------------------------
>
> Key: HDFS-8046
> URL: https://issues.apache.org/jira/browse/HDFS-8046
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Fix For: 2.8.0
>
> Attachments: HDFS-8046.v1.patch
>
>
> On busy clusters, users performing quota checks against a big directory
> structure can affect the namenode performance. It has become a lot better
> after HDFS-4995, but as clusters get bigger and busier, it is apparent that
> we need finer grain control to avoid long read lock causing throughput drop.
> Even with unfair namesystem lock setting, a long read lock (10s of
> milliseconds) can starve many readers and especially writers. So the locking
> duration should be reduced, which can be done by imposing a lower
> count-per-iteration limit in the existing implementation. But HDFS-4995 came
> with a fixed amount of sleep between locks. This needs to be made
> configurable, so that {{getContentSummary()}} doesn't get exceedingly slow.
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