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  1. JDK
  2. JDK-8329134

Reconsider TLAB zapping

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    • gc
    • b17

    Backports

      Description

        We zap the entire TLAB on initial allocation (MemAllocator::mem_allocate_inside_tlab_slow), and then also rezap the object contents when object is allocated from the TLAB (ThreadLocalAllocBuffer::allocate). The second part seems excessive, given the TLAB is already fully zapped.

        There is also no way to disable this zapping, like you would in other places with the relevant Zap* flags.

        Fixing both these issues allows to improve fastdebug tests performance, e.g. in jcstress.

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            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8333409 Reconsider TLAB zapping

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8333449 Reconsider TLAB zapping

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8333450 Reconsider TLAB zapping

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved
            relates to

            Enhancement - null CODETOOLS-7903703 jcstress: Better performance for debug JVMs by disabling unnecessary debugging helpers

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved
            links to

            Commit Commit openjdk/jdk17u-dev/09ad130f

            Commit Commit openjdk/jdk21u-dev/56668630

            Commit Commit openjdk/jdk22u/1f73c981

            Commit Commit openjdk/jdk/5698f7ad

            Review Review openjdk/jdk17u-dev/2510

            Review Review openjdk/jdk21u-dev/627

            Review Review openjdk/jdk22u/233

            Review Review openjdk/jdk/18500

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                shade Aleksey Shipilev
                shade Aleksey Shipilev
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