Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8160369

Memory fences needed around setting and reading object lengths

    XMLWordPrintable

Details

    • Bug
    • Resolution: Fixed
    • P2
    • 9
    • 9
    • hotspot
    • None
    • gc

    Description

      The size of arrays and java.lang.Class instances are stored in "length" and "oop_size" fields within the object. The contract for object initialization is that once the object header has been set non-zero (the klass field in particular), the object is parsable by concurrent GCs.

      Although the source code is writing the fields in the correct order (after JDK-8158946 is fixed), there are no memory fences to ensure that the compiler or CPU doesn't reorder the writes or reads of these fields.

      Attachments

        Issue Links

          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8166811 Missing memory fences between memory allocation and refinement

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8158946 btree009 fails with assert(s > 0) failed: Bad size calculated

          • P2 - Crashes, loss of data, severe memory leak.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8159864 gc/stress/TestStressRSetCoarsening.java hits assert assert(ILocked()) failed: invariant

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Activity

            People

              kbarrett Kim Barrett
              drwhite Derek White
              Votes:
              0 Vote for this issue
              Watchers:
              7 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved: