This may be a known issue but just in case. The heap dumper needs to be updated to work with MVM. If jmap or other tools attempt to obtain a heap dump then the VM core dumps (easy to duplicate - see attached for a sample hs_err file).

$ java -XRunMServer&
[1] 23068
$ MServer > listening on port 1586

$ java -XUseMServer Test

$ jmap -dump:file=heap.bin 23068
Dumping heap to /tmp/foo.bin ...
Exception in thread "main" java.io.IOException: Premature EOF
        at sun.tools.attach.HotSpotVirtualMachine.readInt(HotSpotVirtualMachine.java:244)
        at sun.tools.attach.SolarisVirtualMachine.execute(SolarisVirtualMachine.java:135)
        at sun.tools.attach.HotSpotVirtualMachine.executeCommand(HotSpotVirtualMachine.java:213)
        at sun.tools.attach.HotSpotVirtualMachine.dumpHeap(HotSpotVirtualMachine.java:180)
        at sun.tools.jmap.JMap.dump(JMap.java:242)
        at sun.tools.jmap.JMap.main(JMap.java:140)

#
# An unexpected error has been detected by Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0xfd9c3ae7, pid=23068, tid=3
#
# Java VM: OpenJDK Client VM with MultiApp Extensions enabled (12.0-b01-internal-fastdebug mixed mode solaris-x86)
# Problematic frame:
# V [libjvm.so+0x3c3ae7]
#
# An error report file with more information is saved as:
# /net/rialto/export/Scratch/ab23780/ws/mvm/jdk/build/solaris-i586/mtask/bin/hs_err_pid23068.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#
Current thread is 3
Dumping core ...
Abort