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From "Yi Liu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-7045) Fix deadlock of open file (in some cases)
Date Thu, 11 Sep 2014 08:54:34 GMT

    [ https://issues.apache.org/jira/browse/HDFS-7045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14129795#comment-14129795
] 

Yi Liu commented on HDFS-7045:
------------------------------

Will attach the patch later.

> Fix deadlock of open file (in some cases)
> -----------------------------------------
>
>                 Key: HDFS-7045
>                 URL: https://issues.apache.org/jira/browse/HDFS-7045
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>            Reporter: Yi Liu
>            Assignee: Yi Liu
>            Priority: Critical
>
> There will be deadlock for current logic as following ({{resolvePath}} could throw exception,
then deadlock):
> In {{FSNamesystem#getBlockLocationsUpdateTimes}}:
> {code}
> ...
>      if (isReadOp) { // first attempt is with readlock
>         checkOperation(OperationCategory.READ);
>         readLock();
>       }  else { // second attempt is with  write lock
>         checkOperation(OperationCategory.WRITE);
>         writeLock(); // writelock is needed to set accesstime
>       }
>       src = resolvePath(src, pathComponents);
>       try {
>         ...
>       } finally {
>         if (isReadOp) {
>           readUnlock();
>         } else {
>           writeUnlock();
>         }
>       }
> {code}



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