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  1. Hadoop HDFS
  2. HDFS-2421

Improve the concurrency of SerialNumberMap in NameNode

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Details

    • Improvement
    • Status: Closed
    • Major
    • Resolution: Fixed
    • None
    • 0.23.3, 2.0.2-alpha
    • namenode
    • None
    • Reviewed

    Description

      After enabled permission checking in our HDFS test cluster, our benchmark observed a significant reduced concurrency in NameNode. Investigation showed that most threads were blocked at acquiring the lock of org.apache.hadoop.hdfs.server.namenode.SerialNumberManager$SerialNumberMap. We used concurrentHashMap to replace Hashmap + synchronized methods, which greatly improved the situation.

      Attachments

        1. HDFS-2421.patch
          2 kB
          Jing Zhao
        2. performance_10000_op.png
          59 kB
          Jing Zhao
        3. performance_100000_op.png
          48 kB
          Jing Zhao
        4. performance_SerialNumberManager.png
          55 kB
          Jing Zhao
        5. TestSerialNumberManager.java
          4 kB
          Jing Zhao

        Issue Links

          relates to

          Improvement - An improvement or enhancement to an existing feature or task. HDFS-3805 A small improvement of SerialNumberManager$SerialNumberMap.get

          • Trivial - Cosmetic problem like misspelt words or misaligned text.
          • Resolved

          Activity

            People

              jingzhao Jing Zhao
              hairong Hairong Kuang
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              Dates

                Created:
                Updated:
                Resolved: