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Posted to common-issues@hadoop.apache.org by "Chen He (JIRA)" <ji...@apache.org> on 2015/04/01 20:10:54 UTC

[jira] [Created] (HADOOP-11786) Fix Javadoc typos in org.apache.hadoop.fs.FileSystem

Chen He created HADOOP-11786:
--------------------------------

             Summary: Fix Javadoc typos in org.apache.hadoop.fs.FileSystem
                 Key: HADOOP-11786
                 URL: https://issues.apache.org/jira/browse/HADOOP-11786
             Project: Hadoop Common
          Issue Type: Bug
          Components: documentation
    Affects Versions: 2.6.0
            Reporter: Chen He
            Assignee: Yanjun Wang
            Priority: Trivial


    /**
     * Resets all statistics to 0.
     *
     * In order to reset, we add up all the thread-local statistics data, and
     * set rootData to the negative of that.
     *
     * This may seem like a counterintuitive way to reset the statsitics.  Why
     * can't we just zero out all the thread-local data?  Well, thread-local
     * data can only be modified by the thread that owns it.  If we tried to
     * modify the thread-local data from this thread, our modification might get
     * interleaved with a read-modify-write operation done by the thread that
     * owns the data.  That would result in our update getting lost.
     *
     * The approach used here avoids this problem because it only ever reads
     * (not writes) the thread-local data.  Both reads and writes to rootData
     * are done under the lock, so we're free to modify rootData from any thread
     * that holds the lock.
     */

etc.



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