[hibernate-dev] intermittent NPE during an AS7 testsuite run (with Hibernate 4.0.0.Beta1)

[Scott Marlow]

The NPE bug is addressed by 
https://github.com/jbossas/jboss-as/commit/6fb2053524d04655413d7fbe82adf9058e3952c3

The NPE occurred because the AS7 PU service was closed pre-maturely 
before the EM was.

I added logging for when we create the container managed EMF and when we 
close it.  That makes it clearer what happened for case like this.

Scott

On 06/22/2011 02:09 PM, Steve Ebersole wrote:
> As for the nullness, you can see this if the ServiceRegistry is reused.
> I have not come up with a good solution for that aside from us
> explicitly checking (after adding needed method to ask) that the passed
> registry is still valid.
>
> Not getting the concern here about concurrency. The map and list in
> question are immutable after the registry instantiation is complete,
> which has to happen on a single thread. But its way complicated to code
> that. We would need a "InitializationContext" or something to hold them
> during the constructor processing. I used a ConcurrentHashMp because
> sure it will be *accessed* concurrently. This is stuff held at the
> SessionFactory level.
>
>
> On 06/22/2011 11:00 AM, Scott Marlow wrote:
>> Also appears that AbstractServiceRegistryImpl.serviceList is a mutable
>> object and accessed through a mutable object reference.
>> AbstractServiceRegistryImpl.serviceList should also be changed to an
>> immutable object reference (final and let
>> AbstractServiceRegistryImpl.destroy just clear it).
>>
>> Something also needs to be done to make updates to the
>> AbstractServiceRegistryImpl.serviceList object thread safe (used to
>> ensure services are destroyed in reverse order). Maybe Steve should
>> make this change, so he can choose the concurrent data structure (maybe
>> CopyOnWriteArrayList?) Or maybe rolling our own concurrent ArrayList
>> for needs like this.
>>
>> I'd jump on IRC but the place I'm at this week, seems to be blocking
>> freenode irc...
>>
>> On 06/22/2011 11:30 AM, Scott Marlow wrote:
>>> Good point, it should be "final".
>>>
>>> I'll make that change (if not done already).
>>>
>>> On 06/22/2011 11:20 AM, Emmanuel Bernard wrote:
>>>> Could it be some thread concurrency visibility?
>>>> Since it's a concurrent hashmap, I'd venture it's accessed
>>>> concurrently :)
>>>>
>>>> Try and make the variable final (or volatile) to ensure proper
>>>> visibility across threads.
>>>>
>>>> On 22 juin 2011, at 02:44, Scott Marlow wrote:
>>>>
>>>>> I'm not sure if we will see this NPE again but found the location
>>>>> interesting. I wanted to report the failure in case it happens
>>>>> again in
>>>>> the future or anyone else is interested in playing detective for
>>>>> mysteries like this. ;)
>>>>>
>>>>> The exception call stack is here http://pastie.org/2104060
>>>>>
>>>>> It looks to me like AbstractServiceRegistryImpl.serviceBindingMap is
>>>>> null for some reason. It makes me wonder if
>>>>> AbstractServiceRegistryImpl.destroy() was called prematurely for some
>>>>> reason (for some unexpected reason).
>>>>>
>>>>> I wanted to mention the NPE here in case it happens again, so we
>>>>> can see
>>>>> what is in common with this one. Next time, we will have to capture
>>>>> the
>>>>> AS server.log output which might have additional clues but didn't
>>>>> this time.
>>>>>
>>>>> Scott
>>>>> _______________________________________________
>>>>> hibernate-dev mailing list
>>>>> hibernate-dev at lists.jboss.org
>>>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>>
>>>
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