libjdwp crash while debugging application ran on OpenJDK 16

[S A]

Hi all,

my colleagues recently ran into a crash in libjdwp, when measuring
performance with OpenJDK 17 (early access build). The same crash was
observed with OpenJDK 16.0.1, but not with OpenJDK 15.

We are hoping to get a fix for the crash, before the official OpenJDK 17
release. We've opened a RHEL bugzilla ticket for this (
https://bugzilla.redhat.com/show_bug.cgi?id=1972529), but we expect this
won't be enough to resolve the crash before the release.

What would the appropriate medium be to report the problem? I assume this
mailing list is not the right place, but I don't know how to otherwise
reach out to OpenJDK developers and maintainers (other than via RHEL
support/bugzilla, which is often a slow process).

Sorry for the noise on the mailing list.

Best regards,
Simeon

*Extra infos and background:*

We would like to move to OpenJDK 17, in order to use Shenandoah GC.
Shenandoah GC shows promising results for our product, though only with the
fix for https://bugs.openjdk.java.net/browse/JDK-8254315. We would not be
able to switch (or even evaluate the switch properly) until the crash is
resolved.

Unfortunately we have no reproducer outside of our product, and our
reproducer is quite complex. Trivial use cases of debugging OpenJDK 16 with
Eclipse (we base our product on Eclipse) do not run into a crash.

A fast debug build for OpenJDK 16 reports an assertion fail as follows:

#  Internal Error
(/tmp/jep2604_fastdebug_jdk16/jdk16/src/hotspot/share/runtime/jniHandles.cpp:148),
pid=81289, tid=56880
#  assert(!is_jweak(handle)) failed: wrong method for detroying jweak
#
# JRE version: OpenJDK Runtime Environment (16.0) (fastdebug build
16-internal+0-adhoc.sandreev.jdk16)
# Java VM: OpenJDK 64-Bit Server VM (fastdebug
16-internal+0-adhoc.sandreev.jdk16, mixed mode, tiered, compressed oops, g1
gc, linux-amd64)
# Problematic frame:
# V  [libjvm.so+0x1043cb4]  JNIHandles::destroy_global(_jobject*)+0x224
...
Stack: [0x00007ffe3c4f5000,0x00007ffe3c5f6000],  sp=0x00007ffe3c5f4be0,
 free space=1022k
Native frames: (J=compiled Java code, A=aot compiled Java code,
j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x1043cb4]  JNIHandles::destroy_global(_jobject*)+0x224
V  [libjvm.so+0xfafd9f]  jni_DeleteGlobalRef+0x10f
C  [libjdwp.so+0xf11a]  deleteNode+0x7a
C  [libjdwp.so+0xf71f]  commonRef_reset+0x6f
C  [libjdwp.so+0x10dec]  debugInit_reset+0x6c
C  [libjdwp.so+0x270a2]  acceptThread+0xa2
V  [libjvm.so+0x127c054]  JvmtiAgentThread::call_start_function()+0x1d4
V  [libjvm.so+0x1a51e9a]  JavaThread::thread_main_inner()+0x5ba
V  [libjvm.so+0x1a589e0]  Thread::call_run()+0x100
V  [libjvm.so+0x15fbd26]  thread_native_entry(Thread*)+0x116

Going through the stack trace, looking for related changes, I've not been
able to reproduce the crash with this commit reverted:
https://github.com/openjdk/jdk/commit/79f1dfb8d3941377da77e73f7bbab93baef29b8e