How to spot memory leaks in profiler?

Question

I have an AIR/Flex app I made, I have a few people testing it and everyone is reporting that after leaving it running for a while, it is making all there machines run very slow. It runs fine at first so this must be a memory leak somewhere. I used the profiler on this and the only thing that shows as using a substantial amount of memory is MethodQueueElement which is not a class I wrote, and I have no idea what it does, I am assuming its part of the Flex framework. I am not familiar with using a profiler so I am not sure what all I shuld be looking at, that was the only class that was high on "memory" and it said it had over 100,000 instances. If this is my problem what can I do to fix it? I do not even know what this class does or anything about how it gets instantiated.

Thanks

Answer 1

The MethodQueueElement class is an internal class of the mx.core.UIComponent class. It is used to represent on method call that has been enqueued by a callLater call. The callLater method is part of the public interface of UIComponent, so either you call it in your code, or it is beeing called by the framework (as it happens in UIComponent.setFocus e.g.)

To free all MethodQueueElement instances, UIComponent replaces the current array of MethodQueueElements by a new (empty) one. (in the callLaterDispatcher2 method) So the only way to make a memory leak out of it is, to prevent callLaterDispatcher2 from beeing called.

To debug this, you can start to set breakpoints (while you app is running) in the methods callLater (here your instances get created, so somehow it gets called all the time, look at the stacktrace here!), callLaterDispatcher2 (i suppose it wont get called), and check whether UIComponentGlobals.callLaterSuspendCount is != 0, which could be the reason callLaterDispatcher2 doesn't get called.

Should the latter be the case, i suspect, that you have tweens or something else calling UIComponent.suspendBackgroundProcessing but then not calling resumeBackgroundProcessing (because of an exception terminating the code before reaching the resumeBackgroundProcessing call e.g.)