Under uncertain conditions it can happen that jstack is throwing a NullPointerException:

java.lang.NullPointerException
        at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:88)
        at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:45)
        at sun.jvm.hotspot.tools.JStack.run(JStack.java:66)
        at sun.jvm.hotspot.tools.Tool.startInternal(Tool.java:260)
        at sun.jvm.hotspot.tools.Tool.start(Tool.java:223)
        at sun.jvm.hotspot.tools.Tool.execute(Tool.java:118)
        at sun.jvm.hotspot.tools.JStack.main(JStack.java:92)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at sun.tools.jstack.JStack.runJStackTool(JStack.java:140)
        at sun.tools.jstack.JStack.main(JStack.java:106)
 
I discoveres this when I had running jstack in a bash-driven loop to produce a series of stack snapshots while trying to force a particular failure scenario in the observed VM.

Unfortunately I cannot tell how a generic way to produce this could look like, so presumably it will be best to simply perform a "blind" code review using the above stack trace.