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IZ95392: JAVA 6 SR8 PERFORMANCE ISSUE CAUSED BY INTERPRETER PROFILER STOPPING TOO EARLY AFTER APPLYING APAR IZ69136

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APAR status

  • Closed as program error.

Error description

  • Error Message: Application throughput suffers a 20-30% decrease
    after upgrading from Java 6 SR7 to Java 6 SR9. Running the
    application with the -Xjit:disableInterpreterProfiling option
    reduces the performance of both versions of Java to
    approximately equal levels.
    .
    Stack Trace:
    .
    

Local fix

  • This issue can be worked around using the
    -Xjit:iprofilerSamplesBeforeTurningOff=35000000 option.
    

Problem summary

  • The performance regression was caused by a code change in Java 6
    SR8 which would disable interpreter profiling prematurely. Doing
    so reduced the amount of profile data available to the JIT
    compiler for analysis and optimization, and as a result the
    quality of compiled code would be sub-optimal.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.0 SR10
    .
    The JIT compiler has been updated to avoid the performance
    regression.
    .
    To obtain the fix:
    Install build 20110217 or later
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ95392

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-02-22

  • Closed date

    2011-03-22

  • Last modified date

    2012-01-06

  • 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

    JIT

  • Fixed component ID

    620700124

Applicable component levels

  • R600 PSN

       UP

[{"Line of Business":{"code":"LOB36","label":"IBM Automation"},"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSNVBF","label":"Runtimes for Java Technology"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"6.0"}]

Document Information

Modified date:
06 October 2021