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https://issues.apache.org/jira/browse/HDFS-5276?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13791917#comment-13791917
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Hadoop QA commented on HDFS-5276:
---------------------------------
{color:red}-1 overall{color}. Here are the results of testing the latest
attachment
http://issues.apache.org/jira/secure/attachment/12607862/HDFS-5276.001.patch
against trunk revision .
{color:green}+1 @author{color}. The patch does not contain any @author
tags.
{color:green}+1 tests included{color}. The patch appears to include 1 new
or modified test files.
{color:green}+1 javac{color}. The applied patch does not increase the
total number of javac compiler warnings.
{color:red}-1 javadoc{color}. The javadoc tool appears to have generated 1
warning messages.
{color:green}+1 eclipse:eclipse{color}. The patch built with
eclipse:eclipse.
{color:green}+1 findbugs{color}. The patch does not introduce any new
Findbugs (version 1.3.9) warnings.
{color:green}+1 release audit{color}. The applied patch does not increase
the total number of release audit warnings.
{color:green}+1 core tests{color}. The patch passed unit tests in
hadoop-common-project/hadoop-common.
{color:green}+1 contrib tests{color}. The patch passed contrib unit tests.
Test results:
https://builds.apache.org/job/PreCommit-HDFS-Build/5165//testReport/
Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/5165//console
This message is automatically generated.
> FileSystem.Statistics got performance issue on multi-thread read/write.
> -----------------------------------------------------------------------
>
> Key: HDFS-5276
> URL: https://issues.apache.org/jira/browse/HDFS-5276
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.0.4-alpha
> Reporter: Chengxiang Li
> Assignee: Colin Patrick McCabe
> Attachments: DisableFSReadWriteBytesStat.patch, HDFS-5276.001.patch,
> HDFSStatisticTest.java, hdfs-test.PNG, jstack-trace.PNG, ThreadLocalStat.patch
>
>
> FileSystem.Statistics is a singleton variable for each FS scheme, each
> read/write on HDFS would lead to a AutomicLong.getAndAdd(). AutomicLong does
> not perform well in multi-threads(let's say more than 30 threads). so it may
> cause serious performance issue. during our spark test profile, 32 threads
> read data from HDFS, about 70% cpu time is spent on
> FileSystem.Statistics.incrementBytesRead().
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