On Fri, 8 Mar 2024 03:35:16 GMT, Alex Menkov <amen...@openjdk.org> wrote:
>> Man Cao has updated the pull request incrementally with one additional >> commit since the last revision: >> >> Fix failure under -XX:+UseSerialGC > > Heap dumper was switched to always use segments by > [JDK-8299426](https://bugs.openjdk.org/browse/JDK-8299426) / > [JDK-8321565](https://bugs.openjdk.org/browse/JDK-8321565). > I suppose your fix will cause broken heapdump if there are some unmounted > virtual threads. > You can try to run > test/hotspot/jtreg/serviceability/jvmti/vthread/HeapDump/VThreadInHeapDump.java @alexmenkov Thank you for the quick feedback. I can reproduce the failure with VThreadInHeapDump.java and `-XX:ActiveProcessorCount=1`. The problem seems that the writer cannot write HPROF_FRAME and HPROF_TRACE records in the middle of dumping an HPROF_HEAP_DUMP/HPROF_HEAP_DUMP_SEGMENT, so it resorts to a separate global writer. Do we really need to keep all the HPROF_FRAME and HPROF_TRACE records located together? If not, two possible solutions are: 1. Keep track of all unmounted vthread oops, and dump their stack traces after finishing the HPROF_HEAP_DUMP_SEGMENT. 2. Write an HPROF_HEAP_DUMP_END, dump the vthread's stack trace, then start another HPROF_HEAP_DUMP_SEGMENT. First approach seems resulting in a more organized heap dump. In any case, we probably only need to do this for serial heap dump. Parallel heap dump could keep using the current approach. ------------- PR Comment: https://git.openjdk.org/jdk/pull/18160#issuecomment-1985383273
