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  1. JDK
  2. JDK-8006176

Switch to optimal identity hash code generator

    Details

    • Type: Enhancement
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 9
    • Fix Version/s: 10
    • Component/s: hotspot

      Description

      Reported by one of our customers, relying heavily on System.identityHashCode(...) for their performance. They figured out the global state in current identity hashcode generator penalizes scalability. Their workaround is to switch -XX:hashCode=5 to the thread-local Marsaglia's XorShift generator.

      This issues considers switching -XX:hashCode=5 (or some other generator) by default.

      See also: http://cr.openjdk.java.net/~shade/8006176/randomicity/

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              • Assignee:
                Unassigned
                Reporter:
                shade Aleksey Shipilev
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                • Created:
                  Updated:
                  Resolved: