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  1. JDK
  2. JDK-8160369

Memory fences needed around setting and reading object lengths

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    • Resolution: Fixed
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      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.

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            kbarrett Kim Barrett
            drwhite Derek White
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