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  1. JDK
  2. JDK-8195115

G1 Old Gen MemoryPool CollectionUsage.used values don't reflect mixed GC results

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Details

    • Bug
    • Resolution: Fixed
    • P4
    • 11
    • 8u144, 9.0.1, 10
    • hotspot
    • gc
    • b19
    • generic
    • generic

    Backports

      Description

        The specification for the MemoryPoolMXBean.CollectionUsage says that it "Returns the memory usage after the Java virtual machine most recently expended effort in recycling unused objects in this memory pool." For the two G1 MemoryPools (G1 Young Gen and G1 Old Gen), CollectionUsage.used does not reflect the effect of mixed GCs on G1 Old Gen. For G1 Old Gen, CollectionUsage.used reflects only the effect of a full collection. Reproducer attached.

        A fix is to (1) add the G1 Old Gen MemoryPool to the G1 Young Gen GarbageCollector, and (2) inform the latter when a mixed GC occurs so it can save the state of the G1 Old Gen MemoryPool.

        At Amazon, we find MemoryPool.CollectionUsage to be a more useful metric than MemoryPool.Usage because the former is a much better measure of long term heap occupancy than the latter.

        Attachments

          1. org.tar.gz
            350 kB
          2. GcTest.java
            1 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-8205900 G1 Old Gen MemoryPool CollectionUsage.used values don't reflect mixed GC results

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • 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-8215934 G1 Old Gen MemoryPool CollectionUsage.used values don't reflect mixed GC results

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

            CSR - null JDK-8196719 G1 Old Gen MemoryPool CollectionUsage.used values don't reflect mixed GC results

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8175375 MemoryPoolMXBean.getCollectionUsage() does not works with -XX:+UseG1GC -XX:+ExplicitGCInvokesConcurrent

            • P3 - Major loss of function.
            • Resolved

            Enhancement - null JDK-8196989 Revamp G1 JMX MemoryPool and GarbageCollector MXBean definitions

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8210193 [TESTBUG]gc/g1/mixedgc/TestOldGenCollectionUsage.java fails intermittently with OutOfMemoryError in CDS mode

            • P3 - Major loss of function.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8205344 TraceMemoryManagerStats changes in JDK-8195115 broke ZGC

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8224030 Old Gen usage in MemoryUsage.getCollectionUsage() not updated for young collections

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

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                phh Paul Hohensee
                phh Paul Hohensee
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                Dates

                  Created:
                  Updated:
                  Resolved: