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  1. JDK
  2. JDK-8004888

G1: PSR large heap case shows steady increase in ART

    Details

    • Type: Enhancement
    • Status: Closed
    • Priority: P3
    • Resolution: Not an Issue
    • Affects Version/s: hs23.5, hs25
    • Fix Version/s: 9
    • Component/s: hotspot
    • Subcomponent:
      gc

      Description

      PSR ran with ParOld and G1 and saw ARTs of ~1.15secs and 10.85secs respectively. After plotting the max and average times for the sub-tasks for all pauses for G1GC, I noticed that termination times were following the steady increase in pause time trend and high (single) external root scan time was the reason why.

      A plausible cause could be code cache scanning by a single thread during each pause. For ParOld, I think its alleviated due to the frequent full GCs that cause class unloading.

      After discussing this with John C2, there are a couple of things that can be done:
      1) Add claiming mechanism such that the code cache is not treated as a single root.
      2) There is already a CR for G1 that could help this case for G1: http://bugs.sun.com/view_bug.do?bug_id=7145569

        Attachments

        1. G1.jpg
          G1.jpg
          55 kB
        2. G1.log
          8.73 MB
        3. PO.log
          1.22 MB
        4. PO.png
          PO.png
          36 kB

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              • Assignee:
                Unassigned
                Reporter:
                mbeckwit Monica Beckwith (Inactive)
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                • Created:
                  Updated:
                  Resolved: