Java crashes in HeapDumper

Issue

• On Oracle/Sun JDK 1.6 :
  Our JVM crashed in libjvm's HeapDumper when creating a heap dump:
  [1]

Stack: [0x00007fb3bc1c7000,0x00007fb3bc2c8000],  sp=0x00007fb3bc2c6960,  free space=1022k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x496e2a]  HeapObjectDumper::do_object(oopDesc*)+0x4a
V  [libjvm.so+0x6e332f]  MutableSpace::object_iterate(ObjectClosure*)+0x2f
V  [libjvm.so+0x768101]  PSYoungGen::object_iterate(ObjectClosure*)+0x21
V  [libjvm.so+0x726cce]  ParallelScavengeHeap::object_iterate(ObjectClosure*)+0x1e
V  [libjvm.so+0x72768d]  ParallelScavengeHeap::safe_object_iterate(ObjectClosure*)+0xd
V  [libjvm.so+0x497c11]  VM_HeapDumper::doit()+0x1d1
V  [libjvm.so+0x870a2a]  VM_Operation::evaluate()+0x4a
V  [libjvm.so+0x86fff2]  VMThread::evaluate_operation(VM_Operation*)+0x82
V  [libjvm.so+0x870268]  VMThread::loop()+0x198
V  [libjvm.so+0x86fd6e]  VMThread::run()+0x6e
V  [libjvm.so+0x712eef]  java_start(Thread*)+0x13f

• On Oracle/Sun JDK 1.8.0_144-b01 stacktrace as
  [2]

Stack: [0x00007f02973f4000,0x00007f02974f5000],  sp=0x00007f02974f3880,  free space=1022k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x6960db]  java_lang_Class::signers(oopDesc*)+0x1b
V  [libjvm.so+0x622c4a]  DumperSupport::dump_class_and_array_classes(DumpWriter*, Klass*)+0xba
V  [libjvm.so+0x46b856]  ClassLoaderDataGraph::classes_do(void (*)(Klass*))+0x36
V  [libjvm.so+0x624f29]  VM_HeapDumper::doit()+0x239
V  [libjvm.so+0xad4685]  VM_Operation::evaluate()+0x55
V  [libjvm.so+0xad2a5a]  VMThread::evaluate_operation(VM_Operation*)+0xba
V  [libjvm.so+0xad2dde]  VMThread::loop()+0x1ce
V  [libjvm.so+0xad3250]  VMThread::run()+0x70
V  [libjvm.so+0x92a338]  java_start(Thread*)+0x108
VM_Operation (0x00007f0162a74460): HeapDumper, mode: safepoint, requested by thread 0x00007f01fcd5a000