Thread 9898: (state = IN_JAVA) Error occurred during stack walking: 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:498) at sun.tools.jstack.JStack.runJStackTool(JStack.java:140) at sun.tools.jstack.JStack.main(JStack.java:106)