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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1257) Race condition on FSNamesystem#recentInvalidateSets introduced by HADOOP-5124
Date Fri, 12 Aug 2011 22:07:27 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1257?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13084413#comment-13084413
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Tsz Wo (Nicholas), SZE commented on HDFS-1257:
----------------------------------------------

Hi Eric, thanks for working on this.  Some comments on the patch.

- belongsToInvalidates(..) is not synchronized.

- In dumpRecentInvalidateSets(..), recentInvalidateSets.values().size() is not synchronized.

- In invalidateWorkForOneNode(..), recentInvalidateSets.get(nodeId) is not synchronized.

- Please use junit 4 in the test (i.e. org.junit.* instead of junit.framework.*).

- Suggestion: how about move recentInvalidateSets and the related method to a standalone class?

> Race condition on FSNamesystem#recentInvalidateSets introduced by HADOOP-5124
> -----------------------------------------------------------------------------
>
>                 Key: HDFS-1257
>                 URL: https://issues.apache.org/jira/browse/HDFS-1257
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.23.0
>            Reporter: Ramkumar Vadali
>            Assignee: Eric Payne
>             Fix For: 0.23.0
>
>         Attachments: HDFS-1257.1.20110810.patch, HDFS-1257.2.20110812.patch, HDFS-1257.patch
>
>
> HADOOP-5124 provided some improvements to FSNamesystem#recentInvalidateSets. But it introduced
unprotected access to the data structure recentInvalidateSets. Specifically, FSNamesystem.computeInvalidateWork
accesses recentInvalidateSets without read-lock protection. If there is concurrent activity
(like reducing replication on a file) that adds to recentInvalidateSets, the name-node crashes
with a ConcurrentModificationException.

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