Does an Application memory leak cause an Operating

Question

When we say a program leaks memory, say a new without a delete in c++, does it really leak? I mean, when the program ends, is that memory still allocated to some non-running program and can't be used, or does the OS know what memory was requested by each program, and release it when the program ends? If I run that program a lot of times, will I run out of memory?

Answer 1

The OS can release the memory when the program ends. If a leak exists in a program then it is just an issue whilst the program is running. This is a problem for long running programs such as server processes. Or for example, if your web browser had a memory leak and you kept it running for days then it would gradually consume more memory.

Answer 2

On operating systems with protected memory (Mac OS 10+, all Unix-clones such as Linux, and NT-based Windows systems meaning Windows 2000 and younger), the memory gets released when the program ends.

If you run any program often enough without closing it in between (running more and more instances at the same time), you will eventually run out of memory, regardless of whether there is a memory leak or not, so that's also true of programs with memory leaks. Obviously, programs leaking memory will fill the memory faster than an identical program without memory leaks, but how many times you can run it without filling the memory depends much rather on how much memory that program needs for normal operation than whether there's a memory leak or not. That comparison is really not worth anything unless you are comparing two completely identical programs, one with a memory leak and one without.

Memory leaks become the most serious when you have a program running for a very long time. Classic examples of this is server software, such as web servers. With games or spreadsheet programs or word processors, for instance, memory leaks aren't nearly as serious because you close those programs eventually, freeing up the memory. But of course memory leaks are nasty little beasts which should always be tackled as a matter of principle.

But as stated earlier, all modern operating systems release the memory when the program closes, so even with a memory leak, you won't fill up the memory if you're continuously opening and closing the program.

Answer 3

It's more leaking in the sense that the code itself has no more grip on the piece of memory.