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https://issues.apache.org/jira/browse/HIVE-3098?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13425007#comment-13425007
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Mithun Radhakrishnan commented on HIVE-3098:
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@Daryn: I was about to reply that calling FS.closeAllForUGI(remoteUser) would
be dangerous if the UGI is shared across multiple requests, but that clearly
can't be the case. :] Your suggestion warrants trying out. I'll post results as
soon as I'm done.
@Ashutosh:
1. Yep. UGICache ballooned up more than expected. :]
2. Guava should be interesting.
3. You're right. We were considering the same, if only to do away with the
cleanup thread.
4. I'll keep HadoopShimsSecure in mind. There's also HdfsAuthorizationProvider
to be considered, in HCatalog code.
I'll carry on with implementation iff Daryn's suggestion doesn't work out.
> Memory leak from large number of FileSystem instances in FileSystem.CACHE.
> (Must cache UGIs.)
> ---------------------------------------------------------------------------------------------
>
> 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
> Attachments: 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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