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Posted to common-issues@hadoop.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2017/12/17 17:26:00 UTC
[jira] [Commented] (HADOOP-15124) Slow FileSystem.Statistics
counters
[ https://issues.apache.org/jira/browse/HADOOP-15124?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16294240#comment-16294240 ]
ASF GitHub Bot commented on HADOOP-15124:
-----------------------------------------
GitHub user medb opened a pull request:
https://github.com/apache/hadoop/pull/316
Use LongAdder as FS Statisitcs backend
This is PR for https://issues.apache.org/jira/browse/HADOOP-15124
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/medb/hadoop long-adder-fs-statistics
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/hadoop/pull/316.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #316
----
commit 1ff0d8231374a957fec5d9360f0375bf30a6f818
Author: Igor Dvorzhak <id...@google.com>
Date: 2017-12-16T23:19:34Z
Use LongAdder as FS Statisitcs backend
----
> Slow FileSystem.Statistics counters
> ------------------------------------
>
> Key: HADOOP-15124
> URL: https://issues.apache.org/jira/browse/HADOOP-15124
> Project: Hadoop Common
> Issue Type: Bug
> Components: common
> Affects Versions: 2.9.0, 2.8.3, 2.7.5, 3.0.0
> Reporter: Igor Dvorzhak
>
> While profiling 1TB TeraGen on Hadoop 2.8.2 cluster (Google Dataproc, 2 workers, GCS connector) I saw that FileSystem.Statistics code paths Wall time is 5.58% and CPU time is 26.5% of total execution time.
> After switching FileSystem.Statistics implementation to LongAdder consumed Wall time decreased to 0.006% and CPU time to 0.104% of total execution time.
> Total runtime decreased from 66 mins to 61 mins.
> These results are not conclusive, because I didn't benchmark multiple times to average results, but regardless of performance gains switching to LongAdder simplifies code and reduces its complexity.
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