IBM Support

IV48122: GARBAGE COLLECTION SCAN TIME FOR OWNABLESYNCHRONIZER OBJECTS IS EXCESSIVE

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APAR status

  • Closed as program error.

Error description

  • Error Message: N/A
    .
    Stack Trace: N/A
    .
    Verbose gc log will display mark time for global garbage
    collection cycles. Mark times may be quite high if there is a
    large number of ownableSynchronizer objects to scan. For
    example:
    <gc-op id="16409" type="mark" timems="943.602" contextid="16383"
    timestamp="2013-08-26T12:37:28.838">
      <trace-info objectcount="568592" scancount="529520"
    scanbytes="17031384" />
      <finalization candidates="74580" enqueued="37130" />
      <ownableSynchronizers candidates="3386222" cleared="361251" />
      <references type="soft" candidates="11882" cleared="0"
    enqueued="0" dynamicThreshold="15" maxThreshold="32" />
      <references type="weak" candidates="296775" cleared="115367"
    enqueued="115367" />
      <references type="phantom" candidates="532" cleared="0"
    enqueued="0" />
      <stringconstants candidates="1242969" cleared="663393"  />
    </gc-op>
    

Local fix

Problem summary

  • Some recent garbage collection enhancements (introduced in Java
    7 SR3 and Java 626 SR4) added the tracing of ownableSynchronizer
    objects. The original implementation has shown to have the
    potential to significantly increase global garbage collection
    time.
    

Problem conclusion

  • This defect will be fixed in:
    7.0.0 SR6
    6.0.1 SR7
    .
    The implementation of tracing ownableSynchronizer objects has
    been modified to run much more efficiently.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV48122

  • Reported component name

    J9 COMMON CODE

  • Reported component ID

    620700127

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-09-11

  • Closed date

    2013-09-11

  • Last modified date

    2013-09-11

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    J9 COMMON CODE

  • Fixed component ID

    620700127

Applicable component levels

  • R260 PSY

       UP



Document information

More support for: Runtimes for Java Technology
Virtual Machine

Software version: 260

Reference #: IV48122

Modified date: 11 September 2013