Understanding memory leaks

Hey list,

My app is leaking; It’s actually more of a gush than just a leak.

I tried using the script from http://scottstuff.net/blog/articles/2006/08/17/memory-leak-profiling-with-rails
but to be honest, I couldn’t discern any noticeable pattern from its output. From looking at top and clicking various pages on my site, I have a rough idea where the leak is coming from, but I think I need some help with understanding what exactly is capable of causing them.

I have a class with a bunch of class methods and a class variable (I prefer this approach over singleton instances). Through the cycle of a single request, this class stores various objects in a class variable. At the start of the request, before the class is used, a reset method is called to assign nil to the class variable. At the end of the request, the class is left as-is, with the class variable still populated with objects. Am I correct in my assumption that it doesn’t matter if I call the reset method at the start or end of the request cycle? In production mode, the state of the class should surely be unchanged between requests?

Other than this situation, I fail to see where else in my code a leak could occur. if I ever populate arrays in my controllers or models, they all have method scope so in theory should be collected by the GC when the method returns. Controller classes are instantiated on each request in production mode, right?

Also, can anyone recommend some tools for detecting leaks other than the script mentioned above?

Cheers
Ian

Try Bleak House: http://blog.evanweaver.com/articles/2007/04/28/bleak_house

Some interesting mailing list posts I've found interesting while
inspecting my app are

http://tinyurl.com/2qw6l5

http://tinyurl.com/2rdq2m

Bleak house is definitely the tool to use, and is worth just to try to
stress your app and see if the memory usage just keeps to grow or
stops at some point.

Paolo