I've just fixed a memory leak in my node application which was in the heap of node. I've profiled that with Google's Profiler and managed to fix the memory leak.
Now my app is running again for some time, and I've seen that the heap size is pretty constant. No memory leak anymore. But when I check my server's free RAM, I see a decrease... When I restart my node server the RAM is up to it's normal free RAM. Now I've heard about that Node.js can save objects and stuff outside of the heap. I think that is what's causing the memory leak here.
How can I see what's taking up the memory? Can't really profile anything, or can I?
I'm using:
node.js: v0.8.18 and socket.io: v0.9.13
Some other node modules that I'm using are: nodetime, heapdump (will delete this, though), jquery, crypto, request and querystring.
Some graphs:
Free OS memory and Node RSS and Heap used
Something you can do is use the heapdump module to create a core dump and then you can load it into webkit's web inspector to analyze the memory state of the program. Look at the end of the README in the heapdump module for instructions on loading the heapdump in Google Chrome for instance.
Take a look at this article for a walkthrough of how someone tracked down a memory leak in their program.