[jira] [Created] (HDFS-4451) hdfs balancer exits 1 on success, it should exit 0

["Joshua Blatt (JIRA)" <ji...@apache.org>]

Joshua Blatt created HDFS-4451:
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             Summary: hdfs balancer exits 1 on success, it should exit 0
                 Key: HDFS-4451
                 URL: https://issues.apache.org/jira/browse/HDFS-4451
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: balancer
    Affects Versions: 2.0.2-alpha
         Environment: Centos 6.3, JDK 1.6.0_25
            Reporter: Joshua Blatt


Though the org.apache.hadoop.util.Tool interface javadocs indicate  implementations should return 0 on success, the org.apache.hadoop.hdfs.server.balance.Balancer.Cli implementation returns the int values of this enum instead:

  // Exit status
  enum ReturnStatus {
    SUCCESS(1),
    IN_PROGRESS(0),
    ALREADY_RUNNING(-1),
    NO_MOVE_BLOCK(-2),
    NO_MOVE_PROGRESS(-3),
    IO_EXCEPTION(-4),
    ILLEGAL_ARGS(-5),
    INTERRUPTED(-6);

This created an issue for us when we tried to run the hdfs balancer as a cron job.   Cron sends emails whenever a executable it runs exits non-zero.   We'd either have to disable all emails and miss real issues or fix this bug.

I think both SUCCESS and IN_PROGRESS ReturnStatuses should lead to exit 0.

Marking this change as incompatible because existing scripts which interpret exit 1 as success will be broken (unless they defensively/liberally interpret both exit 1 and exit 0 as success).

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