The Best Memory Leak Definition [closed]

Answer 1

The process in which memory resource are allocated and not properly released once no longer required, often introduced through bad coding practices.

There are built in ways in some languages to help prevent them, although the best way to avoid them is through diligent observation of code execution paths and code reviews. Keeping methods short and singularly purposed helps to keep resource usage tightly scoped and less prone to get lost in the shuffle, as well.

Answer 2

w:

In computer science, a memory leak is a particular type of unintentional memory consumption by a computer program where the program fails to release memory when no longer needed. This condition is normally the result of a bug in a program that prevents it from freeing up memory that it no longer needs.

Answer 3

There are two definitions (at least for me):

Naive definition: Failure to release unreachable memory, which can no longer be allocated again by any process during execution of the allocating process. This can mostly be cured by using GC (Garbage Collection) techniques or detected by automated tools.

Subtle definition: Failure to release reachable memory which is no longer needed for your program to function correctly. This is nearly impossible to detect with automated tools or by programmers who are not familiar with the code. While technically it is not a leak, it has the same implications as the naive one. This is not my own idea only. You can come across projects that are written in a garbage collected language but still mention fixing memory leaks in their changelogs.

Answer 4

All the definitions given here (at the time I wrote this, we have gotten better answers since) fail to address one borderline case:

You have a singleton that allocates memory upon creation and this memory is normally held as long as the program is running even though the current use is done and it's unknown whether any future use will ever be made or not. This is generally done because of the overhead of recreating it.

By the "fail to free when done with it" standard this would be considered a leak and I've seen leak-reporting tools call such things leaks as the memory was still in use. (And in fact the code may not contain code capable of cleaning the object up.)

However, I have encountered code of this nature in compiler libraries before even when the cost of recreating the object isn't all that great.

Leak or not?

Answer 5

edit: This answer is wrong. I'm leaving it up as an example of how easy it is to be mistaken about something you think you know very well. Thank you to everyone who pointed out my mistake.

A memory leak is: A programming error. Your software borrows some memory from the system, uses it, and then fails to return it to the system when it has finished. This means that that particular chunk of memory can never be used by any other programs until the system is rebooted. Many such leaks could use up all of the available memory, resulting in a completely useless system.

To prevent memory leaks, practice RIIA, and always test your software. There are plenty of tools available for this task.