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  1. Hadoop HDFS
  2. HDFS-11586

Report %free, %write_locked, %read_locked for the NameNode FSNamesystemLock

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Details

    • Improvement
    • Status: Open
    • Minor
    • Resolution: Unresolved
    • None
    • None
    • namenode
    • None

    Description

      It's useful to understand how busy the NameNode is by providing these metrics, similar to the %util number from iostat for disks.

      When %free goes to close to 0, we know the NameNode is congested (just like when disk %util goes to 100%).

      This can be implemented very cheaply by using a thread that wakes up every 10ms to check FSNamesystemLock's getReadLockCount() and isWriteLocked() (via the member coarseLock).

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            vagarychen Chen Liang
            zshao Zheng Shao
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              Created:
              Updated: