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  1. JDK
  2. JDK-8140587

Atomic*FieldUpdaters should use Class.isInstance instead of direct class check

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Details

    • Enhancement
    • Status: Resolved
    • P4
    • Resolution: Fixed
    • 9
    • 9
    • core-libs

    Backports

      Description

        There is an anecdotal evidence that replacing direct class checks with Class.isInstance helps when "obj" has subclasses, and "obj.getClass() != tclass" could not be optimized. fullCheck() does Class.isInstance anyway, so it seems functionally correct to use it in the "quick" checks.

                public final int get(T obj) {
                    if (obj == null || obj.getClass() != tclass || cclass != null) fullCheck(obj);
                    return U.getIntVolatile(obj, offset);
                }

                private void fullCheck(T obj) {
                    if (!tclass.isInstance(obj))
                        throw new ClassCastException();
                    if (cclass != null)
                        ensureProtectedAccess(obj);
                }

        This should be checked after JDK-8140483 lands. C1 and C2 may disagree which pattern is faster.

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            backported by

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8144719 Atomic*FieldUpdaters should use Class.isInstance instead of direct class check

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

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8149282 Atomic*FieldUpdaters should use Class.isInstance instead of direct class check

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

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8155427 Atomic*FieldUpdaters should use Class.isInstance instead of direct class check

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

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8175474 Atomic*FieldUpdaters should use Class.isInstance instead of direct class check

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

            Enhancement - null JDK-8140483 Atomic*FieldUpdaters final fields should be trusted

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

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                martin Martin Buchholz
                shade Aleksey Shipilev
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                  Created:
                  Updated:
                  Resolved: