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From "Hudson (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-3098) Memory leak from large number of FileSystem instances in FileSystem.CACHE
Date Wed, 09 Jan 2013 10:28:46 GMT

    [ https://issues.apache.org/jira/browse/HIVE-3098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13548112#comment-13548112
] 

Hudson commented on HIVE-3098:
------------------------------

Integrated in Hive-trunk-hadoop2 #54 (See [https://builds.apache.org/job/Hive-trunk-hadoop2/54/])
    HIVE-3098 : Memory leak from large number of FileSystem instances in FileSystem.CACHE
(Mithun R via Ashutosh Chauhan) (Revision 1382040)

     Result = ABORTED
hashutosh : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1382040
Files : 
* /hive/trunk/metastore/src/java/org/apache/hadoop/hive/metastore/TUGIBasedProcessor.java
* /hive/trunk/shims/src/0.20/java/org/apache/hadoop/hive/shims/Hadoop20Shims.java
* /hive/trunk/shims/src/common-secure/java/org/apache/hadoop/hive/shims/HadoopShimsSecure.java
* /hive/trunk/shims/src/common-secure/java/org/apache/hadoop/hive/thrift/HadoopThriftAuthBridge20S.java
* /hive/trunk/shims/src/common/java/org/apache/hadoop/hive/shims/HadoopShims.java

                
> Memory leak from large number of FileSystem instances in FileSystem.CACHE
> -------------------------------------------------------------------------
>
>                 Key: HIVE-3098
>                 URL: https://issues.apache.org/jira/browse/HIVE-3098
>             Project: Hive
>          Issue Type: Bug
>          Components: Shims
>    Affects Versions: 0.9.0
>         Environment: Running with Hadoop 20.205.0.3+ / 1.0.x with security turned on.
>            Reporter: Mithun Radhakrishnan
>            Assignee: Mithun Radhakrishnan
>             Fix For: 0.10.0, 0.9.1
>
>         Attachments: Hive-3098_(FS_closeAllForUGI()).patch, hive-3098.patch, Hive_3098.patch
>
>
> The problem manifested from stress-testing HCatalog 0.4.1 (as part of testing the Oracle
backend).
> The HCatalog server ran out of memory (-Xmx2048m) when pounded by 60-threads, in under
24 hours. The heap-dump indicates that hadoop::FileSystem.CACHE had 1000000 instances of FileSystem,
whose combined retained-mem consumed the entire heap.
> It boiled down to hadoop::UserGroupInformation::equals() being implemented such that
the "Subject" member is compared for equality ("=="), and not equivalence (".equals()"). This
causes equivalent UGI instances to compare as unequal, and causes a new FileSystem instance
to be created and cached.
> The UGI.equals() is so implemented, incidentally, as a fix for yet another problem (HADOOP-6670);
so it is unlikely that that implementation can be modified.
> The solution for this is to check for UGI equivalence in HCatalog (i.e. in the Hive metastore),
using an cache for UGI instances in the shims.
> I have a patch to fix this. I'll upload it shortly. I just ran an overnight test to confirm
that the memory-leak has been arrested.

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