IZ70114: JAVA JIT - INCORRECTLY STACK ALLOCATING OBJECTS

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Error Message: SIGSEV inside JIT compiled code, or in the
    Garbage Collector. Other types of symptoms are possible like
    crashing in the the interpreter or unexpected exceptions.
    .
    Stack Trace: N/A
    .
    For a method to trigger this problem it must be a rather large
    method (900 or more bytes of bytecodes) and it must have a high
    concentration of calls.
    

Local fix

  • Use the following java command line option to avoid the problem:
    -Xjit:disableEscapeAnalysis
    Using this option may have a slight impact on performance, but
    in most cases it will be less then 1%.
    

Problem summary

  • The JIT will incorrectly determine that it's safe to stack
    allocate an object. The object reference is then leaked into the
    heap and a crash can occur if the GC encounters this reference,
    the object is overwritten by future stack usage, or a truncated
    stack reference is used in a compressed references JVM. It's
    worth noting that this problem is rare and it is difficult to
    determine if a given issue is an example of this problem.
    

Problem conclusion

  • This defect will be fixed in:
    6.0.0 SR8
    5.0.0 SR11 FP2
    .
    The JIT was modified so that it will handle this case by
    correctly determining when objects can not be stack allocated.
    .
    To obtain the fix:
    Install build 20100203 or later
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ70114

  • 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

    2010-02-13

  • Closed date

    2010-02-13

  • Last modified date

    2010-04-29

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

    IZ69974

  • 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 #:

IZ70114

Modified date:

2010-04-29

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