The following test failed in the JDK20 CI:

applications/kitchensink/Kitchensink24HStress.java

Here's a snippet from the log file:

The tail of stress stdout is:
For random generator using seed: -4554880919762113761
To re-run test with same seed value please add "-Djdk.test.lib.random.seed=-4554880919762113761" to command line.
Stress process main method is started.
[9750.598s][warning][gc] GC locker is held; pre-dump GC was skipped
[13671.035s][warning][gc] GC locker is held; pre-dump GC was skipped
[14124.153s][warning][gc] GC locker is held; pre-dump GC was skipped
[24159.340s][warning][gc] GC locker is held; pre-dump GC was skipped
[24591.979s][warning][gc] GC locker is held; pre-dump GC was skipped
[30703.766s][warning][gc] GC locker is held; pre-dump GC was skipped
[33326.421s][warning][gc] GC locker is held; pre-dump GC was skipped
[35903.100s][warning][gc] GC locker is held; pre-dump GC was skipped
[40289.618s][warning][gc] GC locker is held; pre-dump GC was skipped
[54716.844s][warning][gc] GC locker is held; pre-dump GC was skipped
[58636.492s][warning][gc] GC locker is held; pre-dump GC was skipped
[71193.498s][warning][gc] GC locker is held; pre-dump GC was skipped
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007f2d934064e0, pid=1852074, tid=2755448
#
# JRE version: Java(TM) SE Runtime Environment (20.0+15) (build 20-ea+15-995)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (20-ea+15-995, mixed mode, sharing, tiered, compressed oops, compressed class ptrs, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x8c64e0] JfrCheckpointManager::lease(Thread*, bool, unsigned long)+0x70
#
# Core dump will be written. Default location: Core dumps may be processed with "/opt/core.sh %p" (or dumping to /opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S61378/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/5a65d1a0-d544-4113-9107-e10dbe41799f/runs/16080598-87bb-4f8d-831b-bf4ed05a21fe/testoutput/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink24HStress_java/scratch/0/core.1852074)
#
# JFR recording file will be written. Location: /opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S61378/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/5a65d1a0-d544-4113-9107-e10dbe41799f/runs/16080598-87bb-4f8d-831b-bf4ed05a21fe/testoutput/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink24HStress_java/scratch/0/hs_err_pid1852074.jfr
#
Unsupported internal testing APIs have been used.

# An error report file with more information is saved as:
# /opt/mach5/mesos/work_dir/slaves/0c72054a-24ab-4dbb-944f-97f9341a1b96-S61378/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/5a65d1a0-d544-4113-9107-e10dbe41799f/runs/16080598-87bb-4f8d-831b-bf4ed05a21fe/testoutput/test-support/jtreg_closed_test_hotspot_jtreg_applications_kitchensink_Kitchensink24HStress_java/scratch/0/hs_err_pid1852074.log
[thread 2685319 also had an error][thread 2685318 also had an error]


------ Timeout during error reporting after 120 s. ------
----------System.err:(777/68210)----------

Here's the crashing thread's stack:

--------------- T H R E A D ---------------

Current thread (0x00007f2b74a91270): JavaThread "MemAccessWorkerThread" [_thread_new, id=2755448, stack(0x00007f2cb0f82000,0x00007f2cb1083000)]

Stack: [0x00007f2cb0f82000,0x00007f2cb1083000], sp=0x00007f2cb1081c90, free space=1023k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x8c64e0] JfrCheckpointManager::lease(Thread*, bool, unsigned long)+0x70 (jfrIterator.hpp:44)
V [libjvm.so+0x8cdb2c] JfrCheckpointWriter::JfrCheckpointWriter(Thread*, bool, JfrCheckpointType, bool)+0x2c (jfrCheckpointWriter.cpp:49)
V [libjvm.so+0x92f6ea] JfrTypeManager::write_checkpoint(Thread*, unsigned long, oopDesc*)+0x8a (jfrTypeManager.cpp:122)
V [libjvm.so+0x92342c] JfrThreadLocal::on_start(Thread*)+0x9c (jfrThreadLocal.cpp:119)
V [libjvm.so+0xe4756c] Thread::call_run()+0x6c (thread.cpp:211)
V [libjvm.so+0xc7fe18] thread_native_entry(Thread*)+0xd8 (os_linux.cpp:710)


siginfo: si_signo: 11 (SIGSEGV), si_code: 1 (SEGV_MAPERR), si_addr: 0x0000000000008dd8