Question

I have just been trying to fix a few memory leaks in my project and have discovered an interesting problem. It seems like a vast majority of my ‘Point’ objects are not being picked up by the Garbage Collector. Each frame it creates about 5000 new Point objects and less than 10% of them seem to ever get picked up. Even when you use code like this:

var tempPoint :Point = new Point();
tempPoint = null;

Even if I repeat it over 500 times, only a tiny fraction seem to be erased. This is really stating to get on my nerves now and I was wondering if anyone has encountered this before, knows how to solve it / get around it, or cares to enlighten me on what exactly I am doing wrong.

Would love to know anyone’s thoughts on this

ps. I am using The Miner to check the resource usage

Edit: Have now done a quick check where I had the program running for about an hour and although the memory usage went up about 140MB it did start garbage collecting at this point and did not go past that. So they will be picked up but not until you have several million created 😉

Answer 1

I will quote Grant Skinner to answer your question:

A very important thing to understand about the Garbage Collector in FP9 is that it’s operations are deferred. Your objects will not be removed immediately when all active references are deleted, instead they will be removed at some indeterminate time in the future (from a developer standpoint).

[…]

It’s very important to remember that you have no control over when your objects will be deallocated, so you must make them as inert as possible when you are finished with them.

So, what’s happened with your code? FP created something near 5000 instances of Point. If you look the memory usage over time you may notice that it will drop to the initial value after a few seconds.

The best way to avoid this behaviour is to pool the created objects and reuse them instead of creating a new one.