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  1. JDK
  2. JDK-8080623

CPU overhead in FJ due to spinning in awaitWork

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        The patch JDK-8056248 improved FJ handling of threads and removed the risk over starting and activating too many threads. This came with a slight performance impact for streams and FJ work on smaller data sets, which was mitigated by adding extra spinning checking for work before the FJworker-threads go to sleep. The claiming of a task is much faster from a spinning thread than from a thread that first need to be unparked.

        Unfortunately the spinning has shown to be fairly CPU intensive causing overall performance regressions in applications due to less CPU available for the other parts of the application not running as FJ tasks.

        The recommendation which has been discussed with Doug Lea is to disable the spinning for JDK 8, and for JDK 9 continue the ongoing Work and research to solve the active waiting without spinning. Depending on timing of this work it may potentially be back ported to a later release of 8u.

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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-8080768 CPU overhead in FJ due to spinning in awaitWork

            • P3 - Major loss of function.
            • 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-8084254 CPU overhead in FJ due to spinning in awaitWork

            • P3 - Major loss of function.
            • 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-8086205 CPU overhead in FJ due to spinning in awaitWork

            • P3 - Major loss of function.
            • 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-8086925 CPU overhead in FJ due to spinning in awaitWork

            • P3 - Major loss of function.
            • 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-8138046 CPU overhead in FJ due to spinning in awaitWork

            • P3 - Major loss of function.
            • Resolved
            duplicates

            Bug - A problem which impairs or prevents the functions of the product. JDK-8080919 Perf: SPECjb2013 critical jOPs - up to 50% regressed

            • P1 - Blocks development and/or testing work, production could not run.
            • Closed
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-8080919 Perf: SPECjb2013 critical jOPs - up to 50% regressed

            • P1 - Blocks development and/or testing work, production could not run.
            • Closed

            Bug - A problem which impairs or prevents the functions of the product. JDK-8056248 Improve ForkJoin thread throttling

            • P3 - Major loss of function.
            • Closed

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                psandoz Paul Sandoz
                sfriberg Staffan Friberg (Inactive)
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