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Experiences w/ Garbage Collection and C/C++?

Posted by Cliff on from the taking-out-the-trash dept.

dberger queries: "Java has helped garbage collection enter the mainstream programmer's life - but it's certainly not new or unique to java. There have been (and are) several ways to add garbage collection to C/C++ - the most active seeming to be Hans Boehm's free libgc. I'm curious if any of the Slashdot crowd has used this (or any other) C++ garbage collector in non-trivial commercial applications. If so - what were your experiences? If not, why not? (Before you ask, yes - I know that GC isn't the only difference between C++ and Java, but 'automagic memory management' is certainly part of Java's marketing luster)"

3 of 112 comments (clear)

  1. Certainly.. by QuantumG · · Score: 4, Interesting
    Have a look at our project Boomerang. We're over 230k lines of code and we garbage collect everything. It's as easy as linking to Hans Boehm's libgc and adding the following lines to one of your files (probably best is the one which contains "main").

    void* operator new(size_t n) {
    return GC_malloc(n);
    }

    void operator delete(void* p) {
    }

    You can also mix collected memory with uncollected memory, but we really don't see the point. This way we can still have descructors which do useful things but the actual memory clean up is left to the garbage collector. Of course, as we write more and more new code we leave our deletes and our destructors out, and eventually we'll go through and remove them all. Until then, we can disable the garbage collector just by #if 0ing these lines out.

    --
    How we know is more important than what we know.
  2. It's okay by Anonymous Coward · · Score: 4, Interesting

    I've used a garbage collection system in a C project before and it works surprisingly well. The problem with GC in C though is that it is possible and legal to,

    o allocate memory
    o write the pointer to a disk
    o lose the pointer in memory
    o read the pointer back off the disk,
    o make use of the pointer

    With all GC strategies I'm aware of, by the time you read the pointer from the disk the memory may well have been freed.

    I'm not saying that this style of programming is a generally good idea but it is used in certain, specialised situations and therefore not suitable for a garbage collecting language.

  3. Re:Use More Manageable Types by Javagator · · Score: 5, Interesting

    I was part of a project to write an image display system of about 100k lines of C++ code. Our coding standards required that we allocate resources in constructors, release them in destructors, and put objects on the stack when possible. When putting objects on the stack was not possible, we used smart pointers.

    Towards the end of the project, we finally got our company to spring for Purify. We ran Purify on the code and found a few places where we forgot to release a graphics context, and one place where we didn't follow our coding standards, but no other memory leaks. We than ran purify on a comparable C system and found hundreds of memory leaks.

    Proper use of constructors and destructors can make resource management virtually automatic.