Integrated: 8291065: Creating a VarHandle for a static field triggers class initialization

[Chen Liang]

On Fri, 5 May 2023 04:48:09 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

This pull request has now been integrated.

Changeset: 201e3bcf
Author:    Chen Liang <liach at openjdk.org>
Committer: Mandy Chung <mchung at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/201e3bcf52cac64510d50fbdfcd522638d1d0442
Stats:     796 lines in 10 files changed: 636 ins; 52 del; 108 mod

8291065: Creating a VarHandle for a static field triggers class initialization

Reviewed-by: mchung, psandoz

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PR: https://git.openjdk.org/jdk/pull/13821