memory leak in httpd or child process (what is a memory leak)

[Robert Brockway]

On Tue, 20 Dec 2005, paul sutton wrote:

> For the benefit of those who don't know what this is could someone please 
> explain what a memory leak is.

Hi Paul.  A memory leak is when a process consumes more memory than it 
releases.  Since the process eventually goes on to claim additional memory 
it can eventually start to consume so much that it impacts the rest of the 
system.  How quickly this happens depends on how bad the leak is and how 
demanding the process is.  The leak Teddy describes seems fairly bad to 
me.

Memory leaks are quite common in software.  Tools exist to assist in 
locating them and ideally production quality applications would not have 
such bugs.

As Teddy notes, a work around is to periodically restart the application 
to allow the kernel to free the memory for the rest of the system but this 
is far from ideal in a production environment.

In Linux you can impose a limitation on how much memory the process can 
consume.  This will prevent a memory leak taking out the entire system but 
it doesn't help the process itself which would eventually crash.

When you have a memory leak in the kernel itself the only solution is a 
reboot fortunately such things are very rare.

Rob

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