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  1. JDK
  2. JDK-8247281 migrate ObjectMonitor::_object to OopStorage
  3. JDK-8253225

Release Note: Object Monitors No Longer Keep Strong References to Their Associated Object

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    Details

    • Type: Sub-task
    • Status: Closed
    • Priority: P5
    • Resolution: Delivered
    • Affects Version/s: 16
    • Fix Version/s: 16
    • Component/s: hotspot
    • Subcomponent:
    • Verification:
      Verified

      Description

      When synchronization is performed on an object, an association is established between the object and the object monitor that implements the synchronization. In the past, the reference from a monitor to its associated object was a strong reference. These strong references would be observable through JVM TI functions that walk the heap (reported as `JVMTI_HEAP_ROOT_MONITOR` or `JVMTI_HEAP_REFERENCE_MONITOR`) and in heap dumps (reported as `HPROF_GC_ROOT_MONITOR_USED`). As of this release, a weak reference is used. These are not observable to JVM TI or heap dumps. Consequently, `JVMTI_HEAP_ROOT_MONITOR`, `JVMTI_HEAP_REFERENCE_MONITOR` and `HPROF_GC_ROOT_MONITOR_USED` are longer reported.

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            Assignee:
            eosterlund Erik Ă–sterlund
            Reporter:
            eosterlund Erik Ă–sterlund
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