The following test failed in the JDK16 CI:

applications/runthese/RunThese30M.java

Here are snippets from the hs_err_pid file:

# Internal Error (t:/workspace/open/src/hotspot/share/jfr/recorder/checkpoint/types/jfrTypeSet.cpp:600), pid=482276, tid=603108
# assert(_class_unload ? true : ((((JfrTraceIdBits::load(class_loader_klass)) & ((1 << 4) << 8)) != 0))) failed: invariant
#
# JRE version: Java(TM) SE Runtime Environment (16.0+24) (fastdebug build 16-ea+24-1522)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 16-ea+24-1522, compiled mode, sharing, tiered, g1 gc, windows-amd64)
# Core dump will be written. Default location: T:\testoutput\test-support\jtreg_closed_test_hotspot_jtreg_applications_runthese_RunThese30M_java\scratch\0\hs_err_pid482276.mdmp
#
# JFR recording file will be written. Location: T:\testoutput\test-support\jtreg_closed_test_hotspot_jtreg_applications_runthese_RunThese30M_java\scratch\0\hs_err_pid482276.jfr

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

Current thread (0x0000023546fce0a0): JavaThread "JFR Recorder Thread" daemon [_thread_in_vm, id=603108, stack(0x00000074c4800000,0x00000074c4900000)]

Stack: [0x00000074c4800000,0x00000074c4900000]
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [jvm.dll+0xae4101] os::platform_print_native_stack+0xf1 (os_windows_x86.cpp:236)
V [jvm.dll+0xd0c4d7] VMError::report+0xfb7 (vmError.cpp:731)
V [jvm.dll+0xd0ddfe] VMError::report_and_die+0x7de (vmError.cpp:1537)
V [jvm.dll+0xd0e514] VMError::report_and_die+0x64 (vmError.cpp:1328)
V [jvm.dll+0x4b8d97] report_vm_error+0x117 (debug.cpp:267)
V [jvm.dll+0x70bac6] write_classloader+0xd6 (jfrTypeSet.cpp:600)
V [jvm.dll+0x709134] JfrTypeWriterHost<JfrPredicatedTypeWriterImplHost<ClassLoaderData const *,SerializePredicate<ClassLoaderData const *>,&write__classloader>,162>::operator()+0x174 (jfrTypeWriterHost.hpp:69)
V [jvm.dll+0x708bd1] CompositeFunctor<ClassLoaderData const *,JfrTypeWriterHost<JfrPredicatedTypeWriterImplHost<ClassLoaderData const *,LeakPredicate<ClassLoaderData const *>,&write__classloader__leakp>,162>,JfrTypeWriterHost<JfrPredicatedTypeWriterImplHost<ClassLoaderData const *,SerializePredicate<ClassLoaderData const *>,&write__classloader>,162> >::operator()+0xc1 (jfrTypeSetUtils.hpp:50)
V [jvm.dll+0x70a195] JfrArtifactCallbackHost<ClassLoaderData const *,CompositeFunctor<ClassLoaderData const *,CompositeFunctor<ClassLoaderData const *,JfrTypeWriterHost<JfrPredicatedTypeWriterImplHost<ClassLoaderData const *,LeakPredicate<ClassLoaderData const *>,&write__classloader__leakp>,162>,JfrTypeWriterHost<JfrPredicatedTypeWriterImplHost<ClassLoaderData const *,SerializePredicate<ClassLoaderData const *>,&write__classloader>,162> >,ClearArtifact<ClassLoaderData const *> > >::do_artifact+0x25 (jfrTypeSetUtils.hpp:65)
V [jvm.dll+0x70a9c6] CLDCallback::do_cld+0xa6 (jfrTypeSet.cpp:653)
V [jvm.dll+0x442b24] ClassLoaderDataGraph::loaded_cld_do+0x194 (classLoaderDataGraph.cpp:351)
V [jvm.dll+0x70bf82] write_classloaders+0x442 (jfrTypeSet.cpp:713)
V [jvm.dll+0x70b81f] JfrTypeSet::serialize+0x8f (jfrTypeSet.cpp:1033)
V [jvm.dll+0x6bc26f] JfrCheckpointManager::write_type_set+0x13f (jfrCheckpointManager.cpp:438)
V [jvm.dll+0x6ef6a4] JfrRecorderService::_write+0x2a4 (jfrRecorderService.cpp:542)
V [jvm.dll+0x6f03fe] JfrRecorderService::rotate+0x1ae (jfrRecorderService.cpp:508)
V [jvm.dll+0x6f15d2] recorderthread_entry+0x232 (jfrRecorderThreadLoop.cpp:80)
V [jvm.dll+0xc9a907] JavaThread::run+0x327 (thread.cpp:1783)
V [jvm.dll+0xc91cd4] Thread::call_run+0x1b4 (thread.cpp:402)
V [jvm.dll+0xae2a6e] thread_native_entry+0x10e (os_windows.cpp:476)
C [ucrtbase.dll+0x1fb80]
C [KERNEL32.DLL+0x84d4]
C [ntdll.dll+0x6e871]

Here are the JVM args from the test task:

-Xcomp -XX:+CreateCoredumpOnCrash -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:+TieredCompilation -XX:-UseBiasedLocking