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  1. JDK
  2. JDK-8152438

Threads may do significant work out of the non-shared overflow buffer

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    • gc
    • b127

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      Description

        Some task queue statistics measurements on BigRamTester (attached) indicate that particularly during mixed gcs a significant part of the gc threads operate out of the local overflow buffer, and in many cases also do so while the shared task queue is not completely full or even completely empty, disallowing other threads to steal and distribute work.

        BigRamTester run options -Xlog:gc*=debug,gc+phases+task=trace,gc+task+stats=trace,gc+refine=info:x.log -Xms20G -Xmx20G BigRamTester on a 2x10x2 machine.

        Look at the attached log file for the task queue stats, particularly the new columns snotfull (indicating that we popped from the overflow queue while the shared queue has not been full) and sempty (indicating that we popped from the overflow queue while shared queue has been empty).

        Relevant patches attached.

        Attachments

          1. 8152438-fix-push-overflow-into-shared-first
            2 kB
          2. BigRamTester.java
            7 kB
          3. enable-taskqueue-stats
            0.5 kB
          4. improved-taskqueue-stats
            2 kB
          5. x.log
            584 kB

          Issue Links

            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-8163286 Threads may do significant work out of the non-shared overflow buffer

            • 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-8166780 Threads may do significant work out of the non-shared overflow buffer

            • 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-8167042 Threads may do significant work out of the non-shared overflow buffer

            • 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-8167047 Threads may do significant work out of the non-shared overflow buffer

            • 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-8167759 Threads may do significant work out of the non-shared overflow buffer

            • 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-8183627 Threads may do significant work out of the non-shared overflow buffer

            • 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-8192194 Threads may do significant work out of the non-shared overflow buffer

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

            Enhancement - null JDK-8156739 Provide a way to move multiple tasks from overflow to regular task queue

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

            Enhancement - null JDK-8156754 Encapsulate task queue policies into queue/task specific classes to use

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

            Enhancement - null JDK-8204689 Add BigRAMTester to repo

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

            Enhancement - null JDK-8280396 G1: Full gc mark stack draining should prefer to make work available to other threads

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

            Enhancement - null JDK-8272774 Allow heap region sizes larger than 32M with larger card table entry sizes

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

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                tschatzl Thomas Schatzl
                tschatzl Thomas Schatzl
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                  Created:
                  Updated:
                  Resolved: