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From "Hadoop QA (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-5010) Reduce the frequency of getCurrentUser() calls from namenode
Date Fri, 19 Jul 2013 01:23:46 GMT

    [ https://issues.apache.org/jira/browse/HDFS-5010?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13713230#comment-13713230
] 

Hadoop QA commented on HDFS-5010:
---------------------------------

{color:red}-1 overall{color}.  Here are the results of testing the latest attachment 
  http://issues.apache.org/jira/secure/attachment/12593091/HDFS-5010.patch
  against trunk revision .

    {color:green}+1 @author{color}.  The patch does not contain any @author tags.

    {color:red}-1 tests included{color}.  The patch doesn't appear to include any new or modified
tests.
                        Please justify why no new tests are needed for this patch.
                        Also please list what manual steps were performed to verify this patch.

    {color:green}+1 javac{color}.  The applied patch does not increase the total number of
javac compiler warnings.

    {color:green}+1 javadoc{color}.  The javadoc tool did not generate any 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-hdfs-project/hadoop-hdfs.

    {color:green}+1 contrib tests{color}.  The patch passed contrib unit tests.

Test results: https://builds.apache.org/job/PreCommit-HDFS-Build/4687//testReport/
Console output: https://builds.apache.org/job/PreCommit-HDFS-Build/4687//console

This message is automatically generated.
                
> Reduce the frequency of getCurrentUser() calls from namenode
> ------------------------------------------------------------
>
>                 Key: HDFS-5010
>                 URL: https://issues.apache.org/jira/browse/HDFS-5010
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode, performance
>    Affects Versions: 2.1.0-beta, 0.23.9
>            Reporter: Kihwal Lee
>            Assignee: Kihwal Lee
>         Attachments: HDFS-5010.patch
>
>
> According to the "worst" jstack of a busy namenode I took, there were 29 BLOCKED handler
threads. All of them were blocked on the UGI class lock. Here is the breakdown:
> - 2 ensureInitialized() - from non static synchronized methods. This Jira will unblock
these.
> - 27 getCurrentUser()
> Among the 27 threads that were blocked at getCurrentUser(),
> - 18 FSPermissionChecker() - from FSNamesystem#getPermissionChecker() in most namenode
RPC methods
> - 8 BlockTokenSecretManager#generateToken() - getBlockLocations()
> - 1 NameNodeRpcServer.mkdirs
> I think FSPermissionChecker can be modified to be created with a passed in UGI. FSNamesystem
can the one already stored in RPC server by calling getRemoteUser(). This will eliminate a
bulk of getCurrentUser() calls from namenode RPC handlers. A similar change can be made to
mkdirs. Block token generation is not as straightforward. Even without it we can eliminate
majority of the calls.

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