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  1. Hadoop Common
  2. HADOOP-2232

Add option to disable nagles algorithm in the IPC Server


    • Type: Improvement
    • Status: Closed
    • Priority: Major
    • Resolution: Fixed
    • Affects Version/s: 0.16.0
    • Fix Version/s: 0.16.0
    • Component/s: ipc
    • Labels:


      While investigating hbase performance, I found a bottleneck caused by
      Nagles algorithm. For some reads I would get a bi-modal distribution
      of read times, with about half the times being around 20ms, and half
      around 200ms. I tracked this down to the well-known interaction between
      Nagle's algorithm and TCP delayed acknowledgments.

      I found that calling setTcpNoDelay(true) on the server's socket
      connection dropped all of my read times back to a constant 20 ms.

      I propose a patch to have this TCP_NODELAY option be configurable. The
      attacked patch allows one to set the TCP_NODELAY option on both the
      client and the server side. Currently this is defaulted to false
      (i.e., with Nagle's enabled).

      To see the effect, I have included a Test which provokes the issue by
      sending a MapWriteable over an IPC call. On my machine this test shows
      a speedup of 117 times when using TCP_NODELAY.

      These tests were done on OSX 10.4. Your milage may very with other
      TCP/IP implementation stacks.


        1. HADOOP-2232-2.patch
          4 kB
          Clint Morgan
        2. HADOOP-2232-1.patch
          9 kB
          Clint Morgan
        3. 2232-3.patch
          4 kB
          Chris Douglas



            • Assignee:
              clint.morgan Clint Morgan
              clint.morgan Clint Morgan
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