I was reproducing another bug and VM seemed to be hang.

I tried jstack on it and it failed:
1429: Unable to open door: target process not responding or HotSpot VM not loaded
The -F option can be used when the target process is not responding

Then I tried jstack -F and the process crashed:
Attaching to process ID 1429, please wait...
Error attaching to process: Attach failed : No such process

Here is part of hs_err:
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (exceptions.cpp:367), pid=1429, tid=6
# fatal error: ExceptionMark destructor expects no pending exceptions
#
# JRE version: 7.0
# Java VM: Java HotSpot(TM) 64-Bit Server VM (20.0-b01 mixed mode solaris-sparc compressed oops)
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#

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

Current thread (0x0000000100250800): JavaThread "Signal Dispatcher" daemon [_thread_in_vm, id=6, stack(0xffffffff77100000,0xffffffff77200000)]

Stack: [0xffffffff77100000,0xffffffff77200000], sp=0xffffffff771fec90, free space=1019k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0xa241f0];; void VMError::report_and_die()+0x678
V [libjvm.so+0x5404c8];; void report_fatal(const char*,int,const char*)+0x50
V [libjvm.so+0x1980e8];; ExceptionMark::~ExceptionMark()+0xa8
V [libjvm.so+0x39cde8];; void AttachListener::init()+0x258
V [libjvm.so+0x39e8ec];; bool AttachListener::is_init_trigger()+0x134
V [libjvm.so+0x2e4618];; void signal_thread_entry(JavaThread*,Thread*)+0xe8
V [libjvm.so+0x290b58];; void JavaThread::run()+0x338
V [libjvm.so+0x8c7730];; java_start+0x280