Re: Memory leak ?

FROM : James Housley
DATE : Mon Mar 28 23:14:40 2005

On Mar 28, 2005, at 3:51 PM, Jean Bovet wrote:

> I have been looking at the memory allocation using the ObjectAlloc
> tool and it seems that all allocated objects are correctly released.
> As Matt Neuburg wrote, we cannot trust the Activity Monitor numbers
> for memory leak so my question is the following: why is the "real
> memory" column under the activity monitor growing up to 70Mb and then
> stays around 50Mb (were it should be 15Mb) ? Is this memory considered
> as "free" ? How can I be sure ?
>


You have to understand that the underlying kernel is Un*x/BSD based. 
Those pages in memory are marked as free usable to the VM subsystem,
but the pages are still in memory at this point.  What this means is
that they are available for the next process that needs them.  The VM
subsystem is not going to actively swap them out because that would be
work with no benefit.  The next step is either another process is going
to allocate them and use them, or they will be swapped out when some
other process needs to swap some of its pages in or back in.  I asked
almost the same question about one of my programs on FreeBSD, a close
relative.

Jim

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