On Wed, 27 Aug 2025 22:21:51 GMT, Chen Liang <li...@openjdk.org> wrote:
>> As observed in [JDK-8366043](https://bugs.openjdk.org/browse/JDK-8366043) >> [lworld] (LIFE = Legacy Idiom For Equality) causes performance regressions. >> Updating HashMap and ConcurrentHashMap to use `java.util.Objects.equals` >> will make it easier to measure performance of options that remove or modify >> the use of `==` >> >> Replace constructs like: >> >> - ((k = e.key) == key || (key != null && >> key.equals(k)))) >> with: >> + Objects.equals(key, k)) >> >> >> The changes in ConcurrentHashMap are a bit different due to the use of null >> as a sentinel. >> >> The order of arguments to the .equals methods must remain the same to ensure >> compatibility. > > src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java line > 682: > >> 680: K ek; >> 681: if (e.hash == h && >> 682: (ek = e.key) != null && Objects.equals(k, ek)) > > Looking at the code in HashMap, I think you can just use `Objects.equals(k, > ek = e.key)`, or just `k.equals(ek = e.key)` because `Object::equals` is > supposed to return false on null. HashMap allows null keys and that is handled separately in each case, not by the `equals` method. "supposed to" is not sufficient when compatibility is concerned. ------------- PR Review Comment: https://git.openjdk.org/valhalla/pull/1536#discussion_r2307434641
