Do Small Memory Leaks Matter Anymore?

Leaks are bugs.

You probably have other bugs too.

When you ship a product, you ship it with known bugs. When you choose which (of the known) bugs to "fix" versus "ship with", you do so based on the cost and risk to fix versus the customer benefit.

Leaks are no different. If it's a small leak that happens during an infrequent operation in a non-server app (e.g. an app that runs for minutes or hours and then shuts down), it might be "ok" in the same way any other bug is ok.

Actually, leaks can be kinda different in one important way, which is that if you are shipping a library/API, you really should fix them, because the customer benefit is enormous (otherwise all your customer 'inherit' your leak, and will be phoning you just as you have to do to talk to 3rd party vendor now).

This is completely a personal decision.

However, if:

So the question I am really asking is, if I know I have a program that leaks, say 40 bytes every time it is run, does that matter?

In this case, I'd say no. The memory will be reclaimed when the program terminates, so if it's only leaking 40 bytes one time during the operation of an executable, that's practically meaningless.

If, however, it's leaking 40 bytes repeatedly, each time you do some operation, that might be more meaningful. The longer running the application, the more significant that becomes.

I would say, though, that fixing memory leaks often is worthwhile, even if the leak is a "meaningless" leak. Memory leaks are typically indicators of some underlying problem, so understanding and correcting the leak will often make your program more reliable over time.