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From "Dmytro Molkov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-1775) getContentSummary should hold the FSNamesystem readlock
Date Tue, 22 Mar 2011 18:30:05 GMT
getContentSummary should hold the FSNamesystem readlock

                 Key: HDFS-1775
                 URL: https://issues.apache.org/jira/browse/HDFS-1775
             Project: Hadoop HDFS
          Issue Type: Bug
            Reporter: Dmytro Molkov
            Assignee: Dmytro Molkov
            Priority: Minor

Right now the getContentSummary call on the namenode only holds the FSDirectory lock, but
not the FSNamesystem lock. What we are seeing because of that is: 
1) getContentSummary takes the read lock on FSDirectory 
2) the write operation comes and takes a write lock on FSNamesystem and waits for getContentSummary
to finish to get a write lock on FSDirectory

As a result other read operations can't be executed. Since getContentSummary can take a while
to execute on large directories, the performance would be improved if we hold a readlock while
doing that.

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