c++ - Are memory leaks ever ok?

Is it ever acceptable to have a memory leak in your C or C++ application?

What if you allocate some memory and use it until the very last line of code in your application (for example, a global object's destructor)? As long as the memory consumption doesn't grow over time, is it OK to trust the OS to free your memory for you when your application terminates (on Windows, Mac, and Linux)? Would you even consider this a real memory leak if the memory was being used continuously until it was freed by the OS.

What if a third party library forced this situation on you? Would refuse to use that third party library no matter how great it otherwise might be?

I only see one practical disadvantage, and that is that these benign leaks will show up with memory leak detection tools as false positives.

Answer

No.

As professionals, the question we should not be asking ourselves is, "Is it ever OK to do this?" but rather "Is there ever a good reason to do this?" And "hunting down that memory leak is a pain" isn't a good reason.

I like to keep things simple. And the simple rule is that my program should have no memory leaks.

That makes my life simple, too. If I detect a memory leak, I eliminate it, rather than run through some elaborate decision tree structure to determine whether it's an "acceptable" memory leak.

It's similar to compiler warnings – will the warning be fatal to my particular application? Maybe not.

But it's ultimately a matter of professional discipline. Tolerating compiler warnings and tolerating memory leaks is a bad habit that will ultimately bite me in the rear.

To take things to an extreme, would it ever be acceptable for a surgeon to leave some piece of operating equipment inside a patient?

Although it is possible that a circumstance could arise where the cost/risk of removing that piece of equipment exceeds the cost/risk of leaving it in, and there could be circumstances where it was harmless, if I saw this question posted on SurgeonOverflow.com and saw any answer other than "no," it would seriously undermine my confidence in the medical profession.

–

If a third party library forced this situation on me, it would lead me to seriously suspect the overall quality of the library in question. It would be as if I test drove a car and found a couple loose washers and nuts in one of the cupholders – it may not be a big deal in itself, but it portrays a lack of commitment to quality, so I would consider alternatives.