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  1. JDK
  2. JDK-8222148

[lworld] Value type check(guard) causes not working lock coarsening optimization.

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      Description

      Valhalla adds a check if object is a value type before synchronization. As result it causes not working lock coarsening optimization.
      For example: performance of small uncontended locks got 2x times slowdown.
      Benchmarks: http://cr.openjdk.java.net/~skuksenko/valhalla/legacy/benchmarks/

      compare: Lock: singleLock vs Lock.doubleLock

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          Bug - A problem which impairs or prevents the functions of the product. JDK-8222149 [lworld] Value type check/guard before synchronization is not hoisted out of the loop

          • P3 - Major loss of function.
          • Closed

          Enhancement - null JDK-8206905 [lworld] Improve handling of monitorenter on value type

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

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              • Assignee:
                roland Roland Westrelin
                Reporter:
                skuksenko Sergey Kuksenko
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                • Created:
                  Updated:
                  Resolved: