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  1. JDK
  2. JDK-8027295

Free CSet takes ~50% of young pause time

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    • gc
    • b08

        In the refworkload/wls_webapp_atomic JSP-HTTPS-POST-3 benchmark freeing the collection set takes ~50% of total pause time with G1.

        Command line to run:

        -showversion -Xmx8g -Xms8g -XX:+UseLargePages -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -XX:G1MaxNewSizePercent=29 -XX:+UseAdaptiveSizePolicy -XX:+AlwaysPreTouch

        See the attached figure wls_webapp_atomic-long-free-cset.png which shows a stacked graph of the pause time time consumers. The gray area represents the Free CSet time.

        The problematic CSet component is most likely cleaning up the sparse table (but needs to be verified).

          1. default.gc.log
            103 kB
          2. free_cset_time_breakdown.ods
            73 kB
          3. free_cset_time_breakdown.png
            free_cset_time_breakdown.png
            40 kB
          4. wls_webapp_atomic-long-free-cset.png
            wls_webapp_atomic-long-free-cset.png
            103 kB

              tschatzl Thomas Schatzl
              tschatzl Thomas Schatzl
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                Created:
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