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  1. JDK
  2. JDK-8260045

Parallel GC: Waiting on ExpandHeap_lock may cause "expansion storm"

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    • Enhancement
    • Resolution: Fixed
    • P4
    • 17
    • 17
    • hotspot
    • gc
    • b10

    Description

      When expanding the old gen heap during young gc, that section of code is guarded by the ExpandHeap_lock. If multiple threads are out of memory (i.e. old gen PLAB), they will queue up on that lock.

      Since the threads after the first getting the ExpandHeap_lock do not retry the allocation, they will blindly expand the heap again, ultimately causing a "heap expansion storm".

      This not only takes lots of time, but also expands the heap unnecessarily.

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              kbarrett Kim Barrett
              tschatzl Thomas Schatzl
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                Created:
                Updated:
                Resolved: