IZ69014: ERRANT ENTRIES FOR TRACETARGET, KICKOFF ATTRIBUTES IN VERBOSEGC

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APAR status

  • Closed as program error.

Error description

  • Error Message: Verbosegc Output showing huge errant values for
    the attributes tracetarget and kickoff.  Here's a sample:
    <con event="kickoff" timestamp="Sat Oct 31 11:34:45 2009">
    
      <stats tenurefreebytes="0" nurseryfreebytes="112131288"
    tracetarget="10145709460442578944" kickoff="1268213682555469598"
    tracerate="1961.12" />
    </con>
    Also an outage for about 5 minutes is observed usually when
    these entries are seen in the verbosegc output.
    .
    Stack Trace: N/A
    .
    

Local fix

  • There is no real work around.  The only solution is to run with
    -Xgcpolicy:opthtruput or to get a VM with the fix.
    

Problem summary

  • This problem is specific to GC policies using concurrent
    collector (that is, gencon or optavgpause). The errant verbosegc
    entries were caused by a divide by 0.  A divide by 0 when using
    floating point values results in a NAN.  When this value is
    converted back to an unsigned integer the number is very large.
    This large number would cause the GC to kick off another
    concurrent collection immediately since the amount of free
    memory would never be larger than this errant number, resulting
    in a consecutive concurrent collections for a few times and
    hence an outage in the customer environment.
    

Problem conclusion

  • This defect will be fixed in:
    5.0.0 SR12
    .
    Concurrent GC code has been updated to check to see how much
    trace work was completed concurrently and if this value is 0
    then do not adjust the kick off value.
    .
    To obtain the fix:
    Install build 20100204 or later
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ69014

  • Reported component name

    JAVA 5 J9 COMMO

  • Reported component ID

    620500127

  • Reported release

    500

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-02-03

  • Closed date

    2010-02-24

  • Last modified date

    2010-02-24

  • 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

    JAVA 5 J9 COMMO

  • Fixed component ID

    620500127

Applicable component levels

  • R500 PSN

       UP



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Document information


More support for:

Runtimes for Java Technology
Virtual Machine

Software version:

5.0

Reference #:

IZ69014

Modified date:

2010-02-24

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