Hadoop Common
  1. Hadoop Common
  2. HADOOP-785

Divide the server and client configurations


    • Type: Improvement Improvement
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: 0.9.0
    • Fix Version/s: 0.15.0
    • Component/s: conf
    • Labels:


      The configuration system is easy to misconfigure and I think we need to strongly divide the server from client configs.

      An example of the problem was a configuration where the task tracker has a hadoop-site.xml that set mapred.reduce.tasks to 1. Therefore, the job tracker had the right number of reduces, but the map task thought there was a single reduce. This lead to a hard to find diagnose failure.

      Therefore, I propose separating out the configuration types as:

      class Configuration;
      // reads site-default.xml, hadoop-default.xml

      class ServerConf extends Configuration;
      // reads hadoop-server.xml, $super

      class DfsServerConf extends ServerConf;
      // reads dfs-server.xml, $super

      class MapRedServerConf extends ServerConf;
      // reads mapred-server.xml, $super

      class ClientConf extends Configuration;
      // reads hadoop-client.xml, $super

      class JobConf extends ClientConf;
      // reads job.xml, $super

      Note in particular, that nothing corresponds to hadoop-site.xml, which overrides both client and server configs. Furthermore, the properties from the *-default.xml files should never be saved into the job.xml.

      1. HADOOP-785_1_20070903.patch
        9 kB
        Arun C Murthy
      2. HADOOP-785_2_20070906.patch
        17 kB
        Arun C Murthy
      3. HADOOP-785_3_20070908.patch
        16 kB
        Arun C Murthy
      4. HADOOP-785_4.patch
        19 kB
        Doug Cutting

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            • Assignee:
              Arun C Murthy
              Owen O'Malley
            • Votes:
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