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IV83132: HANG IN LONG RUNNING LOOP

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APAR status

  • Closed as program error.

Error description

  • Error Message: The Java application appears to hang while
    executing a loop (the loop is running for a long time and is
    always see when sampling the operation of the 'hung' process) -
    the VM does not respond to signals and the process continues to
    consume CPU time.
    .
    Stack Trace: N/A
    .
    

Local fix

  • The problem can be worked around by specifying
    -Xjit:disableLoopVersioner for the compiled methods where the
    hang appears to be occurring. There is a real risk of measurable
    performance degradation with this option.
    

Problem summary

  • In some circumstances the JIT optimizer will create tests ahead
    of loops to test if they are long running - this determines if
    the compiled code should periodically check for interruptions.
    In rare circumstances later optimizations in the JIT can move
    these tests from being before the loop where they were created
    to before the start of other enclosing loops. This motion can
    then cause other optimizations to make incorrect assumptions
    about the behavior of the program and to incorrectly omit
    interruption checks.
    

Problem conclusion

  • The JIT optimizer has been corrected to ensure that the motion
    of tests for long running loops does not lead to interruption
    checks being omitted restoring expected program behavior.
    .
    This APAR will be fixed in the following Java Releases:
       8    SR3       (8.0.3.0)
    .
    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

    IV83132

  • Reported component name

    JIT

  • Reported component ID

    620700124

  • Reported release

    130

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-03-29

  • Closed date

    2016-03-29

  • Last modified date

    2016-03-29

  • 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:
29 March 2016