RFR: 8358535: Changes in ClassValue (JDK-8351996) caused a 1-9% regression in Renaissance-PageRank

[Andrey Turbanov]

On Thu, 7 Aug 2025 16:23:00 GMT, Chen Liang <liach at 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.

test/jdk/java/lang/invoke/ClassValueTest.java line 484:

> 482:     // unrelated entry is removed
> 483:     @Test
> 484:     public void cacheRefreshTest() throws Throwable {

All other test methods in this class use test* naming. Let's follow it for consistency

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PR Review Comment: https://git.openjdk.org/jdk/pull/26679#discussion_r2262867735