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IV43553: JVM CRASHES WHEN IT TRIES TO DECOMMIT JAVA HEAP MEMORY SMALLER T HAN PAGE SIZE

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APAR status

  • Closed as program error.

Error description

  • Error Message: none
    .
    Stack Trace: j9vmem_decommit_memory()
    MM_VirtualMemory::decommitMemory()
    MM_MemoryManager::decommitMemory()
    MM_ConcurrentCardTable::heapRemoveRange()
    MM_ConcurrentGC::heapRemoveRange()
    MM_HeapVirtualMemory::heapRemoveRange()
    MM_MemorySpace::heapRemoveRange()
    MM_MemorySubSpace::heapRemoveRange()
    MM_MemorySubSpace::heapRemoveRange()
    MM_PhysicalSubArenaVirtualMemoryFlat::contract()
    MM_MemorySubSpace::contract()
    MM_MemorySubSpaceUniSpace::performResize()
    MM_ParallelGlobalGC::masterThreadGarbageCollect()
    MM_ConcurrentGC::internalGarbageCollect()
    MM_Collector::garbageCollect()
    MM_MemorySubSpace::systemGarbageCollect()
    MM_MemorySubSpace::systemGarbageCollect()
    MM_MemorySpace::systemGarbageCollect()
    MM_Heap::systemGarbageCollect()
    j9gc_modron_global_collect_with_()
    .
    

Local fix

  • Couple of workarounds are applicable:
    1) Specify -Xms value equal to -Xmx. This would prevent JVM from
    decommitting any java heap memory. This workaround is applicable
    to all platforms.
    2) On Linux and z/OS, JVM tries to decommit java heap memory
    only if -Xsoftmx option is specified on the command line.
    Therefore, removing the -Xsoftmx option to disable decommitting
    can be used as a workaround on Linux and z/OS only.
    

Problem summary

  • The crash happens when GC tries to decommit java heap memory and
    the memory block to be decommitted is less than the page size
    used to allocate the java heap.
    

Problem conclusion

  • This defect will be fixed in:
    7.0.0 SR5
    6.0.1 SR6
    .
    JVM has been updated to correctly handle the situations where
    size of memory block to be decommitted is less than page size.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV43553

  • Reported component name

    J9 COMMON CODE

  • Reported component ID

    620700127

  • Reported release

    260

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-06-03

  • Closed date

    2013-06-03

  • Last modified date

    2013-06-25

  • 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

    J9 COMMON CODE

  • Fixed component ID

    620700127

Applicable component levels

  • R260 PSY

       UP

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Document Information

Modified date:
21 February 2022