How to increase Heap Size?

[rajat123]

Hi Folks!

I'm facing lot of segmentation faults in my code. I tried using some memory debugger like valgrind but all in vain as they make my application a lot slower and due to which my application does not work at all. And so I'm not able to debug my code.

I'm thinking of increasing the Heap Size of system which is a Fedora Core 6, kernel 2.6.18

1. Please suggest if this is a wise idea to increase the heap when there is problem debugging the code?

2. Also, suggest how can I increase the Heap Size of my machine?

3. Is there any harm to system with increase in the heap size?

Thanks and Regards,
Rajat

[lazlow]

I am not sure but I think you may want to increase the stack size. I THINK that the heap is limited by the program and not by the kernel(except when you run out of address space). You might want to look at:

http://www.thescripts.com/forum/post237960-7.html

[nhydra]

You definitely have a problem with the stack variables. Look around and remove any dangerous local variables. it is impossible to get segfault because of stack size in appropriate working program.
do you use some recursion or iteration algorithms? probably this is your problem.
look about this example.

int a (int c){
char asd[256];
for (;
a(12);
}

this will make segfault because of stack overflow. so, do not do this in your code.

[Reisswolf]

I don't see how increasing the size of the heap will necessarily eliminate the segmentation faults.

Try using breakpoints in gdb to see where you are getting the errors. In all likelihood the problem lies in your code, not in the size of the heap.

Roughly speaking, the only way you could end up with segmentation faults in a perfectly coded programme is if some external programme modified (or eliminated) some variable stored in the heap. But Linux would not, or at least should not, allow that, since the kernel runs in the protected mode (which means that the memory area of one programme is protected from the other programmes).

Are you using shared memory in your programme? (Basically, are you using the shmget() function, and its friends, in C?) If so, then check your programme for race conditions to make sure that data integrity is maintained.

Honestly, I don't think the size of the heap is at fault here.