Issue
I've got a program that is running on a headless/embedded Linux box, and under certain circumstances that program seems to be using up quite a bit more memory (as reported by top, etc) than I would expect it to use.
Since the fault condition is difficult to reproduce outside of the actual working environment, and since the embedded box doesn't have niceties like valgrind or gdb installed, what I'd like to do is simply write out the process's heap-memory to a file, which I could then transfer to my development machine and look through at my leisure, to see if I can tell from the contents of the file what kind of data it is that is taking up the bulk of the heap. If I'm lucky there might be a smoking gun like a repeating string or magic-number that comes up a lot, that points me to the place in my code that is either leaking or perhaps just growing a data structure without bounds.
Is there a good way to do this? The only way I can think of would be to force the process to crash and then collect a core dump, but since the fault condition is rare it would be preferable if I could collect the information without crashing the process as a side effect.
Solution
You can read the entire memory space of the process via /proc/pid/mem; You can read /proc/pid/maps to see what is where in the memory space (so you can find the bounds of the heap and read just that). You can attempt to read the data while the process is running (in which case it might be changing while you are reading it), or you can stop the process with a SIGSTOP signal and later resume it with a SIGCONT.
Answered By - Chris Dodd