IZ69167: JAVA JIT - HIGH CPU IN TR_IPROFILER::SEARCHFORSAMPLE()

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Error Message: A TProf profile shows many TR_IProfiler related
    methods taking CPU in the JIT library.
    40202 26.17 java.exe_0834
      MOD  24421 15.90 C:\jre\bin\j9jit24.dll
       SYM 8520 5.55  TR_IProfiler::searchForSample
       SYM 2214 1.44  TR_IProfiler::bcHash
       SYM 2204 1.43  TR_IProfiler::addSampleData
       SYM 2175 1.42  parseBuffer
       SYM 1665 1.08  TR_IProfiler::findOrCreateEntry
    .
    Stack Trace: N/A
    .
    The "JIT Code Cache" segments (listed in javacore files) have
    consumed the maximum amount of memory allowed by the JVM
    resulting in the JIT refusing the compile any more methods
    forcing uncompiled methods to remain executing in the
    interpreter.
    

Local fix

  • The problem can be avoided by using the following java command
    line option: -Xjit:disableInterpreterProfiling
    Note: This option will effect the quality of the code that the
    JIT generates and therefore may have a impact on performance,
    but in cases where this problem is occurring the performance
    loss will be more then made up for by avoiding the interpreter
    profiling overhead.
    

Problem summary

  • When the JIT is unable to compile new methods because the
    maximum allowable memory has already been consumed, all
    uncompiled methods will execute in the interpreter causing an
    increase in the overhead due to interpreter profiling.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.0 SR8
    5.0.0 SR12
    .
    The JIT has been modified so that interpreter profiling will be
    discontinued when JIT memory is low and new methods are unlikely
    to be compiled.
    .
    To obtain the fix:
    Install build 20100210 or later
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ69167

  • Reported component name

    JAVA 5 JIT

  • Reported component ID

    620500124

  • Reported release

    500

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-02-04

  • Closed date

    2010-02-23

  • Last modified date

    2010-07-22

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

    IZ69136

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

Fix information

  • Fixed component name

    JAVA 5 JIT

  • Fixed component ID

    620500124

Applicable component levels

  • R500 PSN

       UP



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Document information


More support for:

Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version:

5.0

Reference #:

IZ69167

Modified date:

2010-07-22

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