RFR: 8291065: Creating a VarHandle for a static field triggers class initialization [v17]
Paul Sandoz
psandoz at openjdk.org
Wed Jun 28 19:22:03 UTC 2023
On Wed, 28 Jun 2023 01:34:30 GMT, Chen Liang <liach at openjdk.org> wrote:
>> This patch implements lazy initialization for VarHandle working on static fields. It has a good initial call performance.
>>
>> We introduce a new internal API, `target()` to unpack a lazy VarHandle in VH implementation methods. If called via MethodHandle, a barrier is added in the MethodHandle instead.
>>
>> The new test ensures the correctness of Lazy VH for both direct and indirect invocation; the performance of MethodHandle version of lazy VH is not yet tested.
>>
>>
>> Benchmark Mode Cnt Score Error Units
>> LazyStaticColdStart.methodHandleCreateEager ss 10 41.490 ± 12.331 us/op
>> LazyStaticColdStart.methodHandleCreateLazy ss 10 21.810 ± 16.964 us/op
>> LazyStaticColdStart.methodHandleInitializeCallEager ss 10 57.860 ± 13.738 us/op
>> LazyStaticColdStart.methodHandleInitializeCallLazy ss 10 93.300 ± 18.858 us/op
>> LazyStaticColdStart.varHandleCreateEager ss 10 39.860 ± 9.362 us/op
>> LazyStaticColdStart.varHandleCreateLazy ss 10 17.630 ± 1.111 us/op
>> LazyStaticColdStart.varHandleInitializeCallEager ss 10 123.170 ± 62.468 us/op
>> LazyStaticColdStart.varHandleInitializeCallLazy ss 10 105.390 ± 41.815 us/op
>
> Chen Liang has updated the pull request incrementally with one additional commit since the last revision:
>
> Comment update from mandy
>
> Co-authored-by: Mandy Chung <mandy.chung at oracle.com>
Marked as reviewed by psandoz (Reviewer).
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PR Review: https://git.openjdk.org/jdk/pull/13821#pullrequestreview-1503820182
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