Skip to main content

Re: gf 3.1.2 hanging, NPE during jstack

No replies
rlubke
Offline
Joined: 2003-08-21
Points: 0

I think your guess is probably as good as mine. :)

Maybe throw this over to the relevant open jdk mailing list and see if
you can get a response from them?

-rl

Bobby Bissett wrote:
> Thanks Ryan,
>
> Yep, two separate process IDs in my history. :) I killed the java
> process the first time and made sure there were no other java
> processes running after that. The server started to come up again but
> hung after a couple minutes (our startup process involves a lot of
> network traffic). My current theory is that something (a technical
> term) was going wrong in the AWS VM where we were running. We rebooted
> the VM and, after a little fiddling with file descriptor limits, got
> everything running again.
>
> So now it's just a matter of curiosity what was causing the jstack error.
>
> Cheers,
> Bobby
>
>
>
> On Tue, Jun 18, 2013 at 12:59 PM, Ryan Lubke > wrote:
>
> Hey Bobby,
>
> Take this with a grain of salt. From what I've read, you may see
> that NPE when attaching to a JVM that has exhausted the heap.
> You state you ran jstack against both hung instances with the same
> result and that when you restarted the first time, it immediately
> hung again.
> Are you 100% certain all processes from the first instance were
> down and you didn't re-attach to those? Seems really odd that the
> server
> would just hang immediately after a restart with the same NPE.
> Just a sanity check :)
>
>
>
>
> Bobby Bissett wrote:
>> Hi all,
>>
>> One of our GF 3.1.2 servers just hung, and after a restart
>> immediately hung again. Running jstack both times gives us an NPE
>> that I haven't seen before. Does anyone know what this might
>> mean? (Google doesn't seem to know much about it except for other
>> examples of it.)
>>
>> Thanks,
>> Bobby
>>
>> -bash-3.2# /jdk1.6.0_31/bin/jstack -F 21102 >
>> /home/robert.bissett/jstack.out2
>> Attaching to process ID 21102, please wait...
>> Debugger attached successfully.
>> Server compiler detected.
>> JVM version is 20.6-b01
>> java.lang.NullPointerException
>> at
>> sun.jvm.hotspot.oops.InstanceKlass.computeSubtypeOf(InstanceKlass.java:426)
>> at sun.jvm.hotspot.oops.Klass.isSubtypeOf(Klass.java:137)
>> at sun.jvm.hotspot.oops.Oop.isA(Oop.java:100)
>> at
>> sun.jvm.hotspot.runtime.DeadlockDetector.print(DeadlockDetector.java:93)
>> at
>> sun.jvm.hotspot.runtime.DeadlockDetector.print(DeadlockDetector.java:39)
>> at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:52)
>> at sun.jvm.hotspot.tools.StackTrace.run(StackTrace.java:45)
>> at sun.jvm.hotspot.tools.JStack.run(JStack.java:60)
>> at sun.jvm.hotspot.tools.Tool.start(Tool.java:221)
>> at sun.jvm.hotspot.tools.JStack.main(JStack.java:86)
>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>> at
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
>> at
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>> at java.lang.reflect.Method.invoke(Method.java:597)
>> at sun.tools.jstack.JStack.runJStackTool(JStack.java:118)
>> at sun.tools.jstack.JStack.main(JStack.java:84)
>
>