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  1. JDK
  2. JDK-8158871

Long response times with G1 and StringDeduplication

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    • Subcomponent:
      gc
    • Resolved In Build:
      b127

      Backports

        Description


        Using JDK 8u92 with -XX:+UseG1GC -XX:+UseStringDeduplication -Xms13g -Xmx13g,
        several observations were made:

        1) During load testing application response times are significantly impacted
        (increase to 14 sec response times; normal response times are 1 sec) during
        the next time string deduplication runs AFTER a concurrent g1 marking cycle;
        further that particular string deduplication takes 14 sec to run.

        2) All other string deduplications appear normal with durations in the <0.2
        sec range.

        3) The impact can be lessened by increasing parallel gc threads however it is
        still quite significant (14 sec impact w/16 threads, 3 sec impact w/83
        threads).

        4) The impact occurs 100% of the time just after a concurrent g1 cycle when
        the next string deduplication runs.

        When String Deduplication was removed, application response times are normal
        throughout the load test even after g1 concurrent cycles.

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                • Assignee:
                  pliden Per Liden
                  Reporter:
                  shadowbug Shadow Bug
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                  • Created:
                    Updated:
                    Resolved: