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From "Jay D. McHugh" <>
Subject Re: Using the Timer Service (in Geronimo)
Date Fri, 29 Aug 2008 21:43:21 GMT

Looks like getting rid of all of my global level variable and nulling
them out once I was done with them allowed enough objects to be garbage

As an extra (and perhaps unneccessary) step, I removed all of the
injected EJBs and switched to looking them up myself in JNDI.  I did
that because I wasn't sure whether I would be able to null out injected
beans (and still have them re-injected later).

Should they be re-injected automatically later?

If they are supposed to be, then I will go ahead and switch back to
using injection.  If they are not, then I will just leave them alone.



Jay D. McHugh wrote:
> Thanks Dain,
> I'll try that.
> Jay
> Dain Sundstrom wrote:
>> On Aug 28, 2008, at 10:13 PM, Jay D. McHugh wrote:
>>> Hello all,
>>> I have a chain of stateless session beans that are being triggered by
>>> the timer service in Geronimo.
>>> But, even though they are being created with single expirations - they
>>> do not seem to be getting destroyed until the entire chain finishes.
>>> For clarity here is what I mean by chain:
>>> Timer1 creates a timer object for Timer2 with a single expiration.
>>> Timer2 creates a timer object for Timer3 with a single expiration.
>>> .
>>> .
>>> .
>>> TimerX creates a timer object for TimerY with a single expiration.
>>> Each successive timer is created as the '@Timeout' method of its
>>> 'parent' is finishing with an expiration date/time one minute in the
>>> future.
>>> Each of the timers is performing some pretty intense data cleansing
>>> work.  So, there is a lot of memory getting allocated at each step.  So
>>> much so that even with no other activity going on, the server often
>>> crashes (runs out of memory or becomes unable to make new database
>>> connections) before it is able to get to the end of the chain.
>>> I added a 'finalize' method and a '@PreDestroy' method for each of the
>>> timers and none of them have been called yet even though fourteen timers
>>> have run and printed out a message to the console indicating that the
>>> 'timeout' method has gotten to the end.
>>> Actually, I just got a heap space error and finally one of the classes
>>> got finalized (two now) but it looks like that is probably all that will
>>> finish 'cleanly'.
>>> Is there a way to nudge those classes so that they finalize?
>> Which instance do you want to be destroyed?  If you mean the stateless
>> bean, they are pooled and typically only destroyed when VM shutdown. 
>> You can disable the pool by setting PoolSize to 0 in which case a new
>> instance will be created and destroyed for each method invocation. 
>> Stateless EJB creation and destruction is not a particularly expensive
>> process unless your bean is doing a lot of work in the create/destroy
>> callbacks.
>> Alternatively, you could null out all of your fields before the timer
>> method exits (or even better as soon as you are done with the data). 
>> This is the most portable way to handle this.
>> -dain

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