On Tue, 27 Jun 2023 13:57:31 GMT, Chen Liang <li...@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:
>
> Rollback VHG changes
src/java.base/share/classes/java/lang/invoke/VarHandle.java line 524:
> 522: /**
> 523: * Direct VH implementations call this method to
> 524: * unwrap lazy initializing VarHandles.
Suggestion:
* Returns the target VarHandle. Subclasses may override this method to
implement
* additional logic for example lazily initializing the declaring class of
a static field var handle.
src/java.base/share/classes/java/lang/invoke/VarHandle.java line 533:
> 531: /**
> 532: * The VarHandle to be passed to {@link #getMethodHandle}, in
> Invokers
> 533: * LambdaForms and VarHandleGuards.
Suggestion:
* Returns the direct target VarHandle. Indirect VarHandle subclasses
should implement
* this method.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/13821#discussion_r1244410195
PR Review Comment: https://git.openjdk.org/jdk/pull/13821#discussion_r1244420089
