Uploaded image for project: 'Hadoop HDFS'
  1. Hadoop HDFS
  2. HDFS-2362 More Improvements on NameNode Scalability
  3. HDFS-2495

Increase granularity of write operations in ReplicationMonitor thus reducing contention for write lock

VotersWatch issueWatchersLinkCloneUpdate Comment AuthorReplace String in CommentUpdate Comment VisibilityDelete Comments
    XMLWordPrintableJSON

Details

    • Sub-task
    • Status: Closed
    • Major
    • Resolution: Fixed
    • 0.23.0
    • 2.0.0-alpha, 0.23.7
    • namenode
    • None
    • Reviewed

    Description

      For processing blocks in ReplicationMonitor (BlockManager.computeReplicationWork), we first obtain a list of blocks to be replicated by calling chooseUnderReplicatedBlocks, and then for each block which was found, we call computeReplicationWorkForBlock. The latter processes a block in three stages, acquiring the writelock twice per call:

      1. obtaining block related info (livenodes, srcnode, etc.) under lock
      2. choosing target for replication
      3. scheduling replication (under lock)

      We would like to change this behaviour and decrease contention for the write lock, by batching blocks and executing 1,2,3, for sets of blocks, rather than for each one separately. This would decrease the number of writeLock to 2, from 2*numberofblocks.

      Also, the info level logging can be pushed outside the writelock.

      Attachments

        1. replicationMon.patch
          17 kB
          Tomasz Nykiel
        2. replicationMon.patch-1
          18 kB
          Tomasz Nykiel

        Activity

          This comment will be Viewable by All Users Viewable by All Users
          Cancel

          People

            tnykiel Tomasz Nykiel
            tnykiel Tomasz Nykiel
            Votes:
            0 Vote for this issue
            Watchers:
            7 Start watching this issue

            Dates

              Created:
              Updated:
              Resolved:

              Slack

                Issue deployment