Process exit memory released?

[vipin_nvk]

When process exit, will the memory that's left undeleted be returned to OS? My application is a C++ application.

[Lost User]

Yes. And JFYI, OS always reclaims memory after the process (application) exits. If your process runs for some time and doesn't care to release unwanted memory then it won't be reclaimed by the OS and the memory "leaks".

...byte till it megahertz... my donation to web rubbish

[Rajesh R Subramanian]

Bleedingfingers gave you the correct answer.

vipin_nvk wrote:

My application is a C++ application.

The language used to build your program is irrelevant. The OS will ALWAYS take it back after your program is done!

It was ever thus, the Neophiles will always rush out and get 'The Latest Thing' at a high price and with all the inherent faults - Dalek Dave.

[vipin_nvk]

If your process runs for some time and doesn't care to release unwanted memory then it won't be reclaimed by the OS and the memory "leaks". This part of your reply is confusing, does it mean that if I allocate memory in my program but fail to release it properly during application exit / if the application has crashed / terminated from the task manager, will this allocated memory (allocated during program execution) will not be returned to the OS and result in memory leak? Thanx in advance

[Lost User]

No no. Suppose you have a code like this in your app

void main()
{
while(true)
{
int *array = new int[100];
}
}

As long as the app runs, you will have memory leak since you aren't deleting the allocated memory. And it doesn't really matter if the app crashes or ends normally, for the OS the app has ceased to exist and it cleans up. It is your (the app's) data files, network connections etc that would encounter trouble when the app crashes. Clear?

...byte till it megahertz... my donation to web rubbish

[vipin_nvk]

Yes, so to my understanding, all the memory allocated using new when a process is running is allocated from the process memory heap and it will be eventually reclaimed by the OS once the process terminates.. right?

[Rajesh R Subramanian]

vipin_nvk wrote:

Yes, so to my understanding, all the memory allocated using new when a process is running is allocated from the process memory heap and it will be eventually reclaimed by the OS once the process terminates.. right?

Right!

It was ever thus, the Neophiles will always rush out and get 'The Latest Thing' at a high price and with all the inherent faults - Dalek Dave.

[Rajesh R Subramanian]

You could read these couple of very good essays: Inside memory allocation[^] Memory damage primer[^] They aren't particularly explaining how the OS reclaims the resources after a process exits, but nevertheless they make a great read.

It was ever thus, the Neophiles will always rush out and get 'The Latest Thing' at a high price and with all the inherent faults - Dalek Dave.

[Cedric Moonen]

In addition to other answer, I just wantewd to say that it is very good practice to always release the memory you are using. This will reduce the risk of memory leaks you will have when the application is running (see another answer about memory leaks).

Cédric Moonen Software developer
Charting control [v3.0] OpenGL game tutorial in C++

[vipin_nvk]

Thanx Rajesh

[Rajesh R Subramanian]

vipin_nvk wrote:

Thanx Rajesh

Ah, how very refreshing to see a polite member. Have a 5 vote from me. :)

It was ever thus, the Neophiles will always rush out and get 'The Latest Thing' at a high price and with all the inherent faults - Dalek Dave.

[Maximilien]

Even if the OS will reclaim the memory, it's no excuse not to clean up yourself. M.

Watched code never compiles.

[Niklas L]

Always clean up your allocated memory. Even though the OS will reclaim the allocated memory, deleting objects (C++) might have important side effects, such as releasing resources in other processes the instance has allocated on construction. This might lead to 'leaks' in other running processes. Also, if you don't properly delete allocated resources, your code will not be reusable in other applications. Cleaning up your own mess is an important part of C++. Clean up.

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