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  1. Hadoop Common
  2. HADOOP-2576

Namenode performance degradation over time



    • Bug
    • Status: Closed
    • Blocker
    • Resolution: Fixed
    • 0.16.0
    • 0.16.0
    • None
    • None


      We have a cluster running the same applications again and again with a high turnover of files.

      The performance of these applications seem to be correlated to the lifetime of the namenode:
      After starting the namenode, the applications need increasingly more time to complete, with about 50% more time after 1 week.

      During that time the namenode average cpu usage increases from typically 10% to 30%, memory usage nearly doubles (although the average amount of data on dfs stays the same), and the average load factor increases by a factor of 2-3 (although not significantly high, <2).

      When looking at the namenode and datanode logs, I see a lot of asks to delete blocks coming from the namenode for blocks not in the blockmap of the datanodes, repeatedly for the same blocks.
      When I counted the number of blocks asked by the namenode to be deleted, I noticed a noticeable increase with the lifetime of the namenode (a factor of 2-3 after 1 week).

      This makes me wonder whether the namenode does not purge the list of invalid blocks from non-existing blocks.

      But independently, the namenode has a degradation issue.


        1. HADOOP-2576.patch
          2 kB
          Raghu Angadi
        2. HADOOP-2576.patch
          4 kB
          Raghu Angadi
        3. HADOOP-2576.patch
          4 kB
          Raghu Angadi
        4. HADOOP-2576.patch
          4 kB
          Raghu Angadi
        5. HADOOP-2576.patch
          4 kB
          Raghu Angadi



            rangadi Raghu Angadi
            ckunz Christian Kunz
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