Understanding Memory Leaks

Question

4.00/5 (2 votes)

See more:

Suppose I have a main() function with only one malloc statement allocating say some 1 gb memory. Also say my system has 1 gb of ram.

C++

main()
{
    malloc(1gb)

    return(0)
}

The program above exits without freeing the memory.

In this case will the 1 gb of heap memory be returned to system on above process termination or has the heap memory permanently leaked and will be available only on system reboot?

I mean if say we start some another process or say the same process again then will they be able to get the 1 gb if heap again?

Posted 25-Oct-12 5:49am

rupeshkp728

Add a Solution

3 solutions

Solution 3

Nope, OS are smart, they do a lot of cleanup when a process terminates (releases memory, file handles, etc.)
Some programmers even relies on that.

Posted 25-Oct-12 7:30am

CPallini

Comments

Nelek 25-Oct-12 13:37pm

Specially the klingons programmers ;P

Sergey Alexandrovich Kryukov 25-Oct-12 15:11pm

Short and to the point, a 5.
--SA

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2012-10-25T06:02:00

Solution 1

All modern operating systems will reclaim all heap memory when the application ends, but embedded systems may not - it depends on how they are written.

Posted 25-Oct-12 6:02am

OriginalGriff

lewax00 · Accepted Answer · 2012-10-25T06:08:00

The memory will be returned to the free memory pool (although, it would be possible to make an OS that did not, but I'm sure Windows, Linux, and OSX manage their memory intelligently enough to reclaim it), because it is given to that process, and when the process is terminated the OS reclaims all resources used by the application.

If you start the same process, it will have to be allocated again, but assuming the memory hasn't been allocated to another process it shouldn't be an issue to do so. It's unlikely you will get the exact same memory again though, because the OS is constantly allocating memory to processes as they request it.

For another process, it depends. If the memory was shared, then it won't be reclaimed, because the other process is still using it. If you mean another process launching afterwards, then it can have that memory allocated to it by the OS if it's free (and it will be if the application shown above has exited).

I think there is (or was, it may no longer be possible) a way to allocate memory that the OS would not reclaim in Windows, leading to a memory leak until reboot, but I don't remember what it was. As for other OS's, I'm not sure, each manages memory in their own way.