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IV78387: JAVA OBJECT HEADER ACCIDENTALLY ZEROED

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APAR status

  • Closed as program error.

Error description

  • Error Message: This can result in a segmentation error raised by
    the Garbage Collector with vmstate=0x0002000f, or various other
    error messages are possible.
    .
    Stack Trace: If the segmentation error is raised by the Garbage
    Collector, the stack trace will look approximately like this:
    MM_ParallelScavenger::copy
    MM_ParallelScavenger::incrementalScanCacheBySlot
    MM_ParallelScavenger::completeScan
    MM_ParallelScavengerRootClearer::scanUnfinalizedObjectsComplete
    MM_RootScanner::scanClearable
    MM_ParallelScavenger::workThreadGarbageCollect
    MM_ParallelDispatcher::slaveEntryPoint
    .
    

Local fix

  • This problem can be avoided by using the following Java option:
    -Xjit:disableExplicitNewInitialization
    

Problem summary

  • The JIT compiler may generate an optimized sequence of code used
    to zero initialize new objects. Doing this has exposed a problem
    where the code that is generated for zero initialization can
    continue past the last field of an object and writes zeros in
    whatever proceeds it in memory, which is likely a header of
    another object.
    

Problem conclusion

  • This problem is related to the ExplicitNewInitialization
    optimization. The JIT compiler has been updated to remove the
    problematic parts of this optimization.
    .
    This APAR will be fixed in the following Java Releases:
       8    SR2       (8.0.2.0)
    .
    Contact your IBM Product's Service Team for these Service
    Refreshes and Fix Packs.
    For those running stand-alone, information about the available
    Service Refreshes and Fix Packs can be found at:
               https://www.ibm.com/developerworks/java/jdk/
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV78387

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    130

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2015-10-26

  • Closed date

    2015-10-26

  • Last modified date

    2015-10-26

  • 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

  • R130 PSY

       UP

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Document Information

Modified date:
26 October 2015