On Thu, 19 Jun 2025 11:01:28 GMT, ExE Boss <d...@openjdk.org> wrote:
>> Per Minborg has updated the pull request with a new target base due to a
>> merge or a rebase. The incremental webrev excludes the unrelated changes
>> brought in by the merge/rebase. The pull request contains eight additional
>> commits since the last revision:
>>
>> - Merge branch 'master' into sv-release-supplier2
>> - Fix performance regression
>> - Clean up
>> - Fix bug
>> - Simplify
>> - Revert to records
>> - Make code more like the old one
>> - Add removable underlying functions
>
> src/java.base/share/classes/jdk/internal/lang/stable/StableSupplier.java line
> 46:
>
>> 44: @Override
>> 45: public T get() {
>> 46: return delegate.orElseSet(underlyingHolder.underlying(),
>> underlyingHolder);
>
> By avoiding reading from `underlyingHolder` when the `StableValue` is already
> set, this can avoid the overhead of a field read from `underlyingHolder`:
> Suggestion:
>
> final Object t = delegate.wrappedContentsAcquire();
> if (t != null) {
> return unwrap(t);
> }
> return delegate.orElseSet(underlyingHolder.underlying(),
> underlyingHolder);
Before this proposal:
Benchmark Mode Cnt Score Error Units
StableSupplierBenchmark.stable avgt 10 1.369 ± 0.019 ns/op
StableSupplierBenchmark.staticStable avgt 10 0.343 ± 0.005 ns/op
StableSupplierBenchmark.staticSupplier avgt 10 0.389 ± 0.008 ns/op
StableSupplierBenchmark.supplier avgt 10 1.739 ± 0.047 ns/op
After this proposal:
Benchmark Mode Cnt Score Error Units
StableSupplierBenchmark.stable avgt 10 1.436 ± 0.120 ns/op
StableSupplierBenchmark.staticStable avgt 10 0.352 ± 0.044 ns/op
StableSupplierBenchmark.staticSupplier avgt 10 0.346 ± 0.016 ns/op
StableSupplierBenchmark.supplier avgt 10 1.588 ± 0.035 ns/op. <-- !
So, it appears to be some gain here.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/25878#discussion_r2156934164
