On Sat, 3 Jun 2023 00:16:23 GMT, Chen Liang <li...@openjdk.org> wrote:

>> Also fixed the bug with NPE in `IndirectVarHandle::isAccessModeSupported`.
>> 
>> A few implementation-detail methods in VarHandle are now documented with the 
>> implied constraints to avoid subtle problems in the future. Changed 
>> `IndirectVarHandle` to call `asDirect` lazily to accomodate the lazy 
>> VarHandle changes. Also changed VarHandleBaseTest to report the whole 
>> incorrect type of exception caught than swallow it and leaving only a 
>> message.
>> 
>> Current problems:
>> - [ ] The lazy var handle is quite slow on the first invocation.
>>    - As seen in the benchmark, users can first call 
>> `Lookup::ensureInitialized` to create an eager handle.
>>    - After that, the lazy handle has a performance on par with the regular 
>> var handle.
>> - [ ] The class-loading-based test is not in a unit test
>>    - The test frameworks don't seem to offer fine-grained control for 
>> class-loading detection or reliable unloading
>> 
>> 
>> Benchmark                                            Mode  Cnt       Score   
>>      Error  Units
>> VarHandleLazyStaticInvocation.initializedInvocation  avgt   30  12.668 ± 
>> 0.069  ns/op
>> VarHandleLazyStaticInvocation.lazyInvocation         avgt   30  12.683 ± 
>> 0.069  ns/op
>> 
>> 
>> Benchmark                                            Mode  Cnt     Score     
>> Error  Units
>> LazyStaticColdStart.methodHandleCreateEager            ss   10    50.980 ±   
>> 9.454  us/op
>> LazyStaticColdStart.methodHandleCreateLazy             ss   10    24.350 ±   
>> 6.701  us/op
>> LazyStaticColdStart.methodHandleInitializeCallEager    ss   10    65.140 ±   
>> 7.552  us/op
>> LazyStaticColdStart.methodHandleInitializeCallLazy     ss   10   118.360 ±  
>> 20.320  us/op
>> LazyStaticColdStart.varHandleCreateEager               ss   10    49.500 ±   
>> 4.277  us/op
>> LazyStaticColdStart.varHandleCreateLazy                ss   10    26.690 ±   
>> 5.157  us/op
>> LazyStaticColdStart.varHandleInitializeCallEager       ss   10    87.930 ±  
>> 12.643  us/op
>> LazyStaticColdStart.varHandleInitializeCallLazy        ss   10  1057.120 ± 
>> 189.810  us/op
>
> Chen Liang has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Remove lazy init of MH, for all invocation of the Lazy VH needs this MH

Yeah, I was referring the performance drop from 0.5ns/op to 12ns/op for botg 
direct and indirect; don't know what caused the problems of general slowdown on 
my end.

Also, is there anything I can do to fix the windows build failures?

-------------

PR Comment: https://git.openjdk.org/jdk/pull/13821#issuecomment-1574509072

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