IV19920: JAVA JIT - RARE PERFORMANCE PROBLEM WITH LARGE APPLICATIONS

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APAR status

  • Closed as program error.

Error description

  • Error Message: JVM slows after a executing for a long time
    without a problem.
    .
    Stack Trace: N/A
    .
    The application needs to be large enough to run into the JIT
    code cache limit. The performance problem will only be
    noticeable in applications executing the same code on several
    threads.
    The performance problem is very hard to hit and it will be
    nearly impossible for customers to hit the problem for a second
    time.
    

Local fix

  • The problem can be avoided by using the following Java command
    line option:
    -Xjit:disableProfiling
    This option will have a negative effect on performance, but not
    to the same extent as is seen when the this problem occurs.
    

Problem summary

  • For hot methods the JIT will generate a "profiling" JIT compiled
    body. The execution of this body collects profiling information
    that is used later when we recompile the method. If we exhaust
    the JIT code cache before the recompile happens we end up being
    stuck executing a profiled body which, under some circumstances
    can have a major performance impact.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.1 SR2
    7.0.0 SR1
    .
    The JIT will avoid making profiled bodies when we are close to
    running out of JIT code cache space.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV19920

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-04-19

  • Closed date

    2012-04-19

  • Last modified date

    2012-04-19

  • 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

  • R260 PSY

       UP



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Document information


More support for:

Runtimes for Java Technology
Just In Time (JIT) Compiler

Software version:

260

Reference #:

IV19920

Modified date:

2012-04-19

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