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  1. JDK
  2. JDK-8027761

Investigate fast-path for scanning only objects with references during gc

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Details

    • Enhancement
    • Resolution: Fixed
    • P3
    • 16
    • hs25, 8
    • hotspot
    • gc
    • b16
    • Fix failed

    Backports

      Description

        During evacuation, after copying an object to survivor space, it is scanned for further references that may need to be fixed up. This scanning involves calling oop_iterate() on the object.

        We noticed that in many benchmarks (dacapo, specjbb) a large part of the copied objects do not contain any references.

        I.e. across all dacapo benchmarks, over all gcs, on average only 63% of objects contain references, on Specjbb2005 only 60% (looking at instanceOops, typeArrayOops and objArrayOops which make up >97% of the objects copied).

        Investigate if it is possible to have a very fast check whether the copied object potentially contains references or not, skipping the oop iteration call otherwise (and hopefully improving performance in the process).

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            backported by

            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-8028405 Investigate fast-path for scanning only objects with references during gc

            • P3 - Major loss of function.
            • Closed
            is cloned by

            Enhancement - null JDK-8253236 [REDO] Investigate fast-path for scanning only objects with references during gc

            • P3 - Major loss of function.
            • Resolved
            relates to

            Enhancement - null JDK-8040978 Investigate fast-path for scanning objects during marking and refinement

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

            Enhancement - null JDK-8253169 [BACKOUT] Improve large object handling during evacuation

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

            Commit Commit openjdk/jdk/dafcf105

            Review Review openjdk/jdk/90

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                kbarrett Kim Barrett
                tschatzl Thomas Schatzl
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                Dates

                  Created:
                  Updated:
                  Resolved: