How do I force a program to appear to run out of memory?

Question

I have a C/C++ program that might be hanging when it runs out of memory. We discovered this by running many copies at the same time. I want to debug the program without completely destroying performance on the development machine. Is there a way to limit the memory available so that a new or malloc will return a NULL pointer after, say, 500K of memory has been requested?

Answer 1

Try turning the question on its head and asking how to limit the amount of memory an OS will allow your process to use.

Try looking into http://ss64.com/bash/ulimit.html

Try say: ulimit -v

Here is another link that's a little old but gives a little more back ground: http://www.network-theory.co.uk/docs/gccintro/gccintro_77.html

Answer 2

One way is to write a wrapper around malloc().

static unsigned int requested =0;  void* my_malloc(size_tamount){     if (requested + amount < LIMIT){        requested+=amount;        return malloc(amount);    }     return NULL } 

Your could use a #define to overload your malloc.

As GMan states, you could overload new / delete operators as well (for the C++ case).

Not sure if that's the best way, or what you are looking for