IV15424: JAVA JIT PERFORMANCE ISSUE AFTER LOADING CLASS

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Error Message: Performance degradation can occur when a large
    number of JIT compiled methods are invalidated by loading a new
    class. In severe cases, the degradation can appear to cause the
    application to hang. System monitoring tools or profilers may
    reveal that a lot of CPU time is consumed by the JIT compiler
    run-time code.
    .
    Stack Trace: Profiling may show significant time spent in
    TR_RuntimeAssumption::isAssumingMethod(void*)
    .
    

Local fix

  • This issue can be worked around with
    -Xjit:disableInvariantArgumentPreexistence
    This may degrade application performance to some extent.
    

Problem summary

  • The problem occurs if:
    1) an application runs for a long time and compiles many methods
    which call a given class,
    2) a second class is loaded which invalidates the previously
    compiled methods, usually by providing an alternative
    implementation of an interface.
    The required clean-up of meta-data associated with the
    invalidated methods may cause a significant pause in application
    processing.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.0 SR11
    6.0.1 SR4
    7.0.0 SR3
    .
    The JIT compiler run-time code has been updated to search for
    and update compiled method meta data in a more efficient manner.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV15424

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-02-16

  • Closed date

    2012-03-02

  • Last modified date

    2012-10-15

  • 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 PSY

       UP



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Document information


More support for:

Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version:

6.0

Reference #:

IV15424

Modified date:

2012-10-15

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