# Internal Error (/home/zgu/ws/jdk/src/hotspot/cpu/x86/frame_x86.cpp:684), pid=1433, tid=1447
# assert(_last_Java_pc == NULL) failed: already walkable
#
# JRE version: OpenJDK Runtime Environment (16.0) (fastdebug build 16-internal+0-adhoc.zgu.jdk)
# Java VM: OpenJDK 64-Bit Server VM (fastdebug 16-internal+0-adhoc.zgu.jdk, mixed mode, sharing, tiered, compressed oops, shenandoah gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0xaccc22] frame::sender_for_entry_frame(RegisterMap*) const+0x192

Seems to quite reproducible when running with -XX:+ShenandoahVerify