On Sun, 4 Jun 2023 13:23:46 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 0.817 ± >> 0.012 ns/op >> VarHandleLazyStaticInvocation.lazyInvocation avgt 30 0.805 ± >> 0.007 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: > > Improve subsequent VH call performance, thanks exeboss src/java.base/share/classes/java/lang/invoke/LazyInitializingVarHandle.java line 125: > 123: cache[i] = callTarget; > 124: } > 125: } Unlike calling `Unsafe::ensureClassInitialized(…)` (which performs its own synchronisation) or writing `true` to `this.initialized` (which is a benign race), updating the lambda forms this way is probably not quite correct to do under a race and probably needs some synchronisation. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/13821#discussion_r1216862767
