Thread: Telling how much free memory there is

  1. #1

    Telling how much free memory there is

    Hi people,

    I seem to have an impossible-to-fix memory leak in my program. To try to fix it, I'd like to be able to tell how much memory is currently available, so I can check if I'm freeing stuff properly at different points in the program. Anyone know how to do this?

    I've tried using system("free") commands (I'm using Linux), but that doesn't seem to work - the amount of free memory listed doesn't change directly after a malloc.

    I'd be grateful for any suggestions...



  2. #2
    Thanks a lot for your reply Salem. From that page you gave is a link to a program called ccmalloc, which I tried out. And it doesn't seem to work very well when it comes to detecting out of bounds errors (guess electric fence is the way to go for that), but it's great for memory leaks. Thanks again!


  3. #3
    Visionary Philosopher Sayeh's Avatar
    Join Date
    Aug 2002
    Make sure you initialize all pointers to zero before using them. After you free a pointer, initialize it to zero again.

    That way, if you try to use a pointer that's been free- you should crash.

    Secondly, at the end of the program, look at all your pointers to see if they are zeroed. if not, you know you missed a free() call somewhere, and you know which pointer(s) you missed.

    You need a debugger to this easily.

    Every malloc() must have a complimentary free().

    This is a trivial issue.
    It is not the spoon that bends, it is you who bends around the spoon.

  4. #4
    ATH0 quzah's Avatar
    Join Date
    Oct 2001
    One way to know how much memory you have free, is to keep calling malloc until malloc fails. When malloc fails, you know you don't have any memory free.

    Hope is the first step on the road to disappointment.

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