[jira] [Created] (HDFS-3651) optionally, the NameNode should invoke saveNamespace after getting a SIGTERM

["Colin Patrick McCabe (JIRA)" <ji...@apache.org>]

Colin Patrick McCabe created HDFS-3651:
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             Summary: optionally, the NameNode should invoke saveNamespace after getting a SIGTERM
                 Key: HDFS-3651
                 URL: https://issues.apache.org/jira/browse/HDFS-3651
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: name-node
    Affects Versions: 2.0.0-alpha
            Reporter: Colin Patrick McCabe
            Assignee: Colin Patrick McCabe
            Priority: Minor


It would be nice if the NameNode could be configured so that it did a saveNamespace and then shut down cleanly after receiving a SIGTERM signal.  In general, it is a good practice to call saveNamespace when doing an orderly shutdown, to ensure that all of the information in the namespace is on disk.  Of course, this should not be necessary if the SecondaryNameNode or StandbyNameNode is operating correctly.  However, when there are bugs in these daemons, a saveNamespace can prevent disaster.

Currently, we don't catch SIGTERM, but just shut down immediately, without doing any cleanup.  Of course, it will always be possible to shut down the NameNode without doing a saveNamespace, simply by sending SIGKILL, which is un-catchable.

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