[Zope] Zope memory usage / cache

[ender]

On Tuesday 30 January 2001 21:21, Ron Bickers wrote:
> > -----Original Message-----
> > From: ender [mailto:kthangavelu@earthlink.net]
> > Sent: Tuesday, January 30, 2001 10:12 AM
> > To: Ron Bickers; zope@zope.org
> > Subject: Re: [Zope] Zope memory usage / cache
> >
> > this sounds like normal operating system behavior. memory isn't
> > being free'd
> > just dealloc and returned to the program heap and marked as available.
>
> Ok.  So you're saying that even though it says it's taking 50MB, much of
> that memory is probably available for other applications?  

warning: i'm on shaky ground here.

this is very os dependent. most os's don't resize a process's heap down on a 
dealloc. instead the heap has more available memory for that process (ie 
Zope), other processes will have to alloc from free memory.

the management of free heap space and disk caching is again os dependent, but 
a good os should try to do some optimization of heaps before thrashing, so 
starting a new process should cause a problem.


>Does this mean
> that if another application actually starts to use that memory that the
> Zope process should start showing a reduction in use? 

no.

> How can I (if I can)
> see how much is really available? 

 i'm not sure how you would do this on linux.


>Also, does the free memory below not
> necessarily reflect the amount of memory that is actually available for
> applications that may need it?

no it does not (again os dependent). free memory is indicator of the os free 
resources for new and current processes. for existing processes it is a 
indicator not a def. answer.

>              total       used       free     shared    buffers     cached
> Mem:        126312     122936       3376      48424       5820      29952
> -/+ buffers/cache:      87164      39148
> Swap:       530104      21876     508228
>
> Sorry if this is inappropriate for the Zope list.  I have only *noticed*
> this behavior with Zope, but that may not mean anything.

if you're on linux trying starting up a large app (gimp comes to mind as a 
good one) and loading and unloading some large docs, and watch what happens


kapil