Sunday, February 15, 2009

Disliking First Steps in Debugging with Tools

I'm dealing with a component grabbing way, way too much memory. In the downloading of a Torrent of size 341Mb, the extension will cause Firefox to consume 2.1Gb of memory. Uncool. The most likely cause of the growth, in my opinion, would be the actual data being received.

I think it should be the case if nothing happens, not much memory will be eaten (though this isn't exactly true, I see a jump of 38Mb when my content type handler component is fired for the first time - this seems a bit much).

So, I'm trying to learn the ways of debugging memory issues in Firefox. I will admit, this is frustrating me more than I've been frustrated in some time. There are several options for finding memory leaks. So far, I've started down the route of gdb. I can start gdb, and that's about it. I was meant to set a breakpoint to watch for garbage collection, but that didn't quite work - perhaps I need a debug build.

I thought I'd try the leaksoup tool. To use that, I've tried a build with trace-malloc enabled. Failed, I get buffer overflows when running the build.

I've tried creating a debug build. That's failed, I get buffer overflows when running the build. Ugh. Perhaps I've installed the wrong pre-requisite?

I've tried just building. That's failed, again with a buffer overflow. Could be bad pre-requisite, or current trunk is bad? I've done another checkout, and building again.

I've tried setting the environment variable XPC_SHUTDOWN_HEAP_DUMP to a filename before running firefox from terminal, but that does nothing. (I shouldn't need a debug build for using this variable, according to )

I found something that looks pretty good - DumpHeap ( ), but darned if I know how to call it. It seems to be concerned with finding objects in a particular scope though, and I doubt my problems are that easy.

I think any debugging route with a debugger (My current lists to try are valgrind and continue with gdb) would require the debug build to make things anywhere near easy, which requires me to resolve why I can't build anything. So I guess that's my current pain. I mean, plan.

1 comment:

  1. Personally, I think doing this in gdb is going to be harder than just using the built in refcnt and leak tools, see to go with your other page. David Baron's screencasts on how to do this are useful too: