On Fri, 23 May 2025 06:48:31 GMT, Joel Sikström <jsiks...@openjdk.org> wrote:
>> Hello, >> >> The goal of this RFE is to separate Metaspace printing from GC printing. The >> main reason Metaspace and GC printing is coupled the way it is right now is >> because historically, the permanent generation (PermGen), which was replaced >> by Metaspace, was part of the GC heap. Hence, it made sense to also print >> info about the PermGen when printing the GC heap. >> >> With Metaspace replacing the PermGen, which uses memory that is separate >> from the GC heap, the coupling has become more loose, raising the question >> if Metaspace should be printed somewhere else (maybe when printing *other* >> Metaspace stuff?). A reason to still print Metaspace when printing the heap >> is that the GC is responsible for unloading classes and nmethods, which >> means it makes sense to print Metaspace information in connection to when a >> GC is performed. >> >> To better reflect the current state of the JVM, I propse we make the >> following changes to separate Metaspace from GC printing: >> * Move Metaspace printing from HeapInfoDCmd to MetaspaceDCmd. >> * Move Metaspace printing from the "Heap:" section to "Metaspace:" section >> in vmError.cpp (hs_err files, the VM.info jcmd and -XX:+PrintVMInfoAtExit). >> * Use gc+exit instead of gc+heap+exit as tags for the LogTarget during exit >> printing to reflect that it's not only the heap being printed. >> * And the largest change in terms of LOC, separate Metaspace and GC Heap >> prints in the before/after GC invocation(s) printing. This is also recorded >> in a ring buffer, which is printed in vmError.cpp. >> >> Testing: >> * GHA, Oracle's tier 1-4 >> * Manuel inspection of printed content > > Joel Sikström has updated the pull request incrementally with one additional > commit since the last revision: > > Add back MetaspaceUtils::print_on() in Metaspace jcmd This looks good to me! I added a small nit. src/hotspot/share/gc/shared/collectedHeap.hpp line 55: > 53: class GCHeapLog; > 54: class MemoryPool; > 55: class GCMetaspaceLog; Sort these ------------- Marked as reviewed by stefank (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/25214#pullrequestreview-2863925232 PR Review Comment: https://git.openjdk.org/jdk/pull/25214#discussion_r2104275736
