Andrus,
After watching the video you suggested, I tried one of the "tricks". I started
up tomcat, with the cayenne enabled app. Then took a snapshot with VisualVM.
There appear to be 5 instances of
org.apache.cayenne.event.EventManager$DispatchThread.run()
This may or may not be normal, however when I redeployed the application (via
ant-tomcat command) there were then 10 instances. Each time I redeployed the
app, another 5 instances were displayed with VisualVM snapshot.
I then tried another test, in which I restarted Tomcat (to get 5 instances of
the EventManager) used Tomcat manager to undeploy the app (which ostensibly
wipes the app from the tomcat dir structure), however, the 5 instances of the
EventManager were still showing up in VisualVM snapshot.
Mark Thomas (the video lecturer), said that this all *might* indicate a leak.
However, since I am unfamiliar with the intended behavior, I cannot be sure.
On the other hand, having these 5 instance multiply each time the app is
redeployed does not seem like it is standard behavior.
Thomas described an on behavior in which just adding a JDBC jar file to your
WEB-INF/lib dir could cause a leak. The reasoning behind how the class loaders
work was a bit convoluted, but I am wondering if these behaviors are related.
So my question is what behavior would you expect, and what should my next test
be?
Joe
On Mar 13, 2012, at 4:47 PM, Andrus Adamchik wrote:
>
> On Mar 13, 2012, at 4:03 PM, Mike Kienenberger wrote:
>
>> 2) Modern app servers restart and redeploy applications without
>> restarting the app server. Thus, the memory leak might be from a
>> previous application instance or application deployment. I think
>> someone reported a possible Cayenne issue for that recently.
>
> I keep recommending to people this presentation by Mark Thomas from Tomcat
> project:
>
> Video with slides: http://www.infoq.com/presentations/Diagnosing-Memory-Leaks
> Slides in PDF:
> people.apache.org/~markt/presentations/2010-11-04-Memory-Leaks-60mins.pdf
>
> Even if you are not using Tomcat, but curious what happens to your memory, I
> still recommend it :) It is applicable to any Java app server and was an eye
> opener to me back in the day.
>
> Andrus
>
