On Thu, 7 Aug 2025 16:23:00 GMT, Chen Liang <li...@openjdk.org> wrote:
> JDK-8351996, PR #24043, updated java.lang.ClassValue, but accidentally missed > a piece of cache refresh code that is meaningful when the cache is > speculatively invalidated by `remove` calls. > > This caused a significant regression in the > [PageRank](https://github.com/renaissance-benchmarks/renaissance/blob/master/benchmarks/apache-spark/src/main/scala/org/renaissance/apache/spark/PageRank.scala) > benchmark, primarily because Scala array creation like `Array.fill` uses > `scala.reflect.ClassTag` which uses `ClassValue`, making `ClassValue.get` a > hot code path for every array creation. src/java.base/share/classes/java/lang/ClassValue.java line 479: > 477: put(classValue.identity, updated); > 478: } > 479: // Add to the cache, to enable the fast path, next time. A question: do we only care about `if (updated != entry)` path for this cache-add then? Should this code be moved into that block? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/26679#discussion_r2260954863
