On Wed, 19 Jun 2024 15:06:25 GMT, Axel Boldt-Christmas <abold...@openjdk.org> wrote:
>> ClassLoaderDataGraph provides APIs for walking different metadata. All the >> iterators which are not designed to be used by the GC also keep the holder >> of the CLDs alive and by extensions keeps all metadata alive. This is >> problematic for concurrent GC as it keeps otherwise unreachable classes from >> being unloaded and the respective metadata freed. >> >> This patch changes the default iteration behaviour to not keep the holder >> alive, with the exception of `loaded_classes_do` (renamed >> `loaded_classes_do_keepalive`) and `modules_do` (renamed >> `modules_do_keepalive`) which is used by jvmti APIs that requires that the >> holder is kept alive. >> >> All other uses consumes all the metadata it queries during its safepoint or >> before releasing the `ClassLoaderDataGraph_lock`. >> >> Before this change some jcmd, new jfr chunks and some jfr events, all of >> which consumed these APIs, could cause class unloading to not occur. >> >> Been running our internal stress test in an even more stressful mode which >> without this patch reproduces the metaspace OOME >> [JDK-8326005](https://bugs.openjdk.org/browse/JDK-8326005) consistently >> within a few hours. And after this patch it does not. >> >> Currently running tier1-tier8 testing. > > Axel Boldt-Christmas has updated the pull request incrementally with one > additional commit since the last revision: > > Rename and comment SystemDictionary::methods_do Marked as reviewed by stefank (Reviewer). ------------- PR Review: https://git.openjdk.org/jdk/pull/19769#pullrequestreview-2128591105
