Overriding global operator new to track huge memory allocations?

Question

I am trying to produce a special build of a large monolithic application. The problem I am trying to solve is tracking hard-to-reproduce huge memory allocations (30-80 gigabytes, judging by what OS reports). I believe the problem is an std::vector resized to a negative 32-bit integer value. The only platform exhibiting this behavior is Solaris (maybe it's the only platform that manages to successfully allocate such chunks of contiguous memory). Can I globally replace std::vector with my class, delegating all calls to the real vector, watching for suspicious allocations (size > 0x7FFFFFFFu)? Maybe selectively replace the constructor that takes size_t and the resize() methods? Maybe even hijacking the global operator new?

Answer 1

Why not to do something like this?

void *operator new(size_t size)
{
    // if (size > MAX_SIZE) ...
    return malloc(size);
}

void *operator new [](size_t size)
{
    // if (size > MAX_SIZE) ...
    return malloc(size);
}

Setting a breakpoint in the if would find the problem right away.

Answer 2

You can provide a custom allocator on your vector at the time it's constructed.

You could just delegate to std::allocator, and firewall the requested memory size, in the first instance.