Question

I have a question out of curiosity relating to checking for memory leaks.

Being someone who has used valgrind frequently to check for memory leaks in my code for the last year or two, I suddenly came to think that it only detects lost/unfreed memory after the life of the program.

So, in light of that, I was thinking that if you have a long-running program which malloc()‘s intermittently and doesn’t free() until the application exits, then the potential to eat memory (not necessarily through leaks) is huge and isn’t observable using these tools because they only check after the programs lifetime. Are there GDB-like tools which can stop an application while running and check for memory which is and isn’t referenced at an instance in the life of the application?

Answer 1

Are there GDB-like tools which can stop an application while running and check for memory which is and isn’t referenced at an instance in the life of the application?

Yes: Valgrind.

Specifically, the SVN version of Valgrind has a gdbserver stub embedded into it.

This allows you to do all kinds of cool debugging, not possible before:

• You can run program under valgrind and have GDB breakpoints at the same time
• You can ask valgrind: is this memory allocated? was this variable initialized?
• You can ask valgrind: what new leaks happened since last time I asked for leaks?

I think you can also ask it to list not-leaked new allocations.