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From "Eric Payne (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-1257) Race condition on FSNamesystem#recentInvalidateSets introduced by HADOOP-5124
Date Wed, 17 Aug 2011 03:12:28 GMT

     [ https://issues.apache.org/jira/browse/HDFS-1257?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Eric Payne updated HDFS-1257:

    Attachment: HDFS-1257.4.20110816.patch

Thanks Nicholas.

> In belongsToInvalidates(..), the call to invalidateSet.contains(block) is not synchronized.

> In computeInvalidateWork(..), the call to recentInvalidateSets.size() is not synchronized.

> In invalidateWorkForOneNode(..), two synchronized block should be combined. Otherwise,
the invalidateSet may be modified in-between.
Done. For invalidateWorkForOneNode(), I also included the blocksToInvalidate processing inside
of the synchronized() section because this is modifying individual invalidateSet lists from
the recentInvalidateSets.

> Is TestProtectedBlockManager reliable? It sometimes timed out in my machine. It would
be great if it can finish within 1 minute.
I changed the processing time from 180 seconds to 55 seconds.

> 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-1257.3.20110815.patch,
HDFS-1257.4.20110816.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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