On Thu, 21 Mar 2024 20:09:23 GMT, Viktor Klang <vkl...@openjdk.org> wrote:
>> Chen Liang has updated the pull request with a new target base due to a >> merge or a rebase. The pull request now contains 13 commits: >> >> - Use the improved form in forEach >> - Merge branch 'master' of https://github.com/openjdk/jdk into >> feature/imm-coll-stream >> - Null checks should probably be in the beginning... >> - mark implicit null checks >> - Merge branch 'master' of https://github.com/openjdk/jdk into >> feature/imm-coll-stream >> - Copyright year, revert changes for non-few element collections >> - Merge branch 'master' of https://github.com/openjdk/jdk into >> feature/imm-coll-stream >> - Merge branch 'feature/imm-coll-stream' of >> https://github.com/liachmodded/jdk into feature/imm-coll-stream >> - Spliterator for 12, iterate/forEach benchmark >> - fix comments >> - ... and 3 more: https://git.openjdk.org/jdk/compare/d5b95a0e...69bd0e9c > > 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. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/15834#discussion_r1534886983
