Hadoop Common
  1. Hadoop Common
  2. HADOOP-8052

Hadoop Metrics2 should emit Float.MAX_VALUE (instead of Double.MAX_VALUE) to avoid making Ganglia's gmetad core

    Details

    • Type: Bug Bug
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: 1.0.0, 0.23.0
    • Fix Version/s: 1.0.1, 0.23.1
    • Component/s: metrics
    • Labels:
      None

      Description

      Ganglia's gmetad converts the doubles emitted by Hadoop's Metrics2 system to strings, and the buffer it uses is 256 bytes wide.

      When the SampleStat.MinMax class (in org.apache.hadoop.metrics2.util) emits its default min value (currently initialized to Double.MAX_VALUE), it ends up causing a buffer overflow in gmetad, which causes it to core, effectively rendering Ganglia useless (for some, the core is continuous; for others who are more fortunate, it's only a one-time Hadoop-startup-time thing).

      The fix needed to Ganglia is simple - the buffer needs to be bumped up to be 512 bytes wide, and all will be well - but instead of requiring a minimum version of Ganglia to work with Hadoop's Metrics2 system, it might be more prudent to just use Float.MAX_VALUE.

      An additional problem caused in librrd (which Ganglia uses beneath-the-covers) by the use of Double.MIN_VALUE (which functions as the default max value) is an underflow when librrd runs the received strings through libc's strtod(), but the librrd code is good enough to check for this, and only emits a warning - moving to Float.MIN_VALUE fixes that as well.

      1. HADOOP-8052.patch
        3 kB
        Varun Kapoor
      2. HADOOP-8052-branch-1.patch
        3 kB
        Varun Kapoor
      3. HADOOP-8052.patch
        1 kB
        Varun Kapoor
      4. HADOOP-8052-branch-1.patch
        1 kB
        Varun Kapoor

        Activity

        Arun C Murthy made changes -
        Status Resolved [ 5 ] Closed [ 6 ]
        Mahadev konar made changes -
        Fix Version/s 0.23.1 [ 12318884 ]
        Fix Version/s 0.23.2 [ 12319855 ]
        Target Version/s 0.23.2, 1.0.1, 0.23.1 [ 12319855, 12319501, 12318884 ] 0.23.1, 1.0.1, 0.23.2 [ 12318884, 12319501, 12319855 ]
        Suresh Srinivas made changes -
        Target Version/s 0.23.2, 1.0.1 [ 12319855, 12319501 ] 0.23.1, 1.0.1, 0.23.2 [ 12318884, 12319501, 12319855 ]
        Matt Foley made changes -
        Labels patch
        Matt Foley made changes -
        Status Patch Available [ 10002 ] Resolved [ 5 ]
        Hadoop Flags Reviewed [ 10343 ]
        Target Version/s 1.0.1, 0.23.1 [ 12319501, 12318884 ] 1.0.1, 0.23.2 [ 12319501, 12319855 ]
        Fix Version/s 1.0.1 [ 12319501 ]
        Fix Version/s 0.23.2 [ 12319855 ]
        Resolution Fixed [ 1 ]
        Varun Kapoor made changes -
        Status Open [ 1 ] Patch Available [ 10002 ]
        Target Version/s 1.0.1, 0.23.1 [ 12319501, 12318884 ] 0.23.1, 1.0.1 [ 12318884, 12319501 ]
        Varun Kapoor made changes -
        Attachment HADOOP-8052.patch [ 12514037 ]
        Varun Kapoor made changes -
        Attachment HADOOP-8052-branch-1.patch [ 12514036 ]
        Varun Kapoor made changes -
        Status Patch Available [ 10002 ] Open [ 1 ]
        Target Version/s 1.0.1, 0.23.1 [ 12319501, 12318884 ] 0.23.1, 1.0.1 [ 12318884, 12319501 ]
        Varun Kapoor made changes -
        Status Open [ 1 ] Patch Available [ 10002 ]
        Target Version/s 1.0.1, 0.23.1 [ 12319501, 12318884 ] 0.23.1, 1.0.1 [ 12318884, 12319501 ]
        Varun Kapoor made changes -
        Attachment HADOOP-8052.patch [ 12514006 ]
        Varun Kapoor made changes -
        Field Original Value New Value
        Attachment HADOOP-8052-branch-1.patch [ 12514005 ]
        Varun Kapoor created issue -

          People

          • Assignee:
            Varun Kapoor
            Reporter:
            Varun Kapoor
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            Watchers:
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            Dates

            • Created:
              Updated:
              Resolved:

              Development