On Fri, 22 Mar 2024 00:21:56 GMT, Chen Liang <li...@openjdk.org> wrote:
>> src/java.base/share/classes/java/util/ImmutableCollections.java line 924: >> >>> 922: action.accept(REVERSE ? (E)e1 : e0); // implicit null >>> check >>> 923: action.accept(REVERSE ? e0 : (E)e1); >>> 924: } >> >> Out of curiosity, how does the following fare performance-wise? >> >> Suggestion: >> >> action.accept((!REVERSE || e1 == EMPTY) ? e0 : (E)e1); // >> implicit null check >> if (e1 != EMPTY) >> action.accept(!REVERSE ? (E)e1 : e0); > > Benchmark Mode Cnt Score Error Units > ImmutableColls.forEachOverList thrpt 15 361.423 ± 8.751 ops/us > ImmutableColls.forEachOverSet thrpt 15 79.158 ± 5.064 ops/us > ImmutableColls.getOrDefault thrpt 15 244.012 ± 0.943 ops/us > ImmutableColls.iterateOverList thrpt 15 152.598 ± 3.687 ops/us > ImmutableColls.iterateOverSet thrpt 15 61.969 ± 4.453 ops/us > > The 3 results are also available at > https://gist.github.com/f0b4336e5b1cf9c5299ebdbcd82232bf, where baseline is > the master this patch currently is based on (which has WhiteBoxResizeTest > failures), patch-0 being the current code, and patch-1 being your proposal > (uncommited patch below). > > diff --git a/src/java.base/share/classes/java/util/ImmutableCollections.java > b/src/java.base/share/classes/java/util/ImmutableCollections.java > index fc232a521fb..f38b093cf60 100644 > --- a/src/java.base/share/classes/java/util/ImmutableCollections.java > +++ b/src/java.base/share/classes/java/util/ImmutableCollections.java > @@ -916,12 +916,9 @@ public <T> T[] toArray(T[] a) { > @Override > @SuppressWarnings("unchecked") > public void forEach(Consumer<? super E> action) { > - if (e1 == EMPTY) { > - action.accept(e0); // implicit null check > - } else { > - action.accept(REVERSE ? (E)e1 : e0); // implicit null check > - action.accept(REVERSE ? e0 : (E)e1); > - } > + action.accept((!REVERSE || e1 == EMPTY) ? e0 : (E) e1); // > implicit null check > + if (e1 != EMPTY) > + action.accept(!REVERSE ? (E) e1 : e0); > } > > @Override > > > > My testing shows that the existing version I have is most likely faster than > your proposed version. > > Also note that the test failures are from WhiteBoxResizeTest that's fixed in > latest master; I decide not to pull as not to invalidate the existing > benchmark baselines. Thanks. I was mostly trying to gauge what the bottleneck might be. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/15834#discussion_r1535286326
