[Zope-dev] is threading in zope useful ?

[Dario Lopez-Kästen]

sathya wrote:

> 
> What about threads on linux ? will binding a process to a CPU also mean 
> all threads spawned by the process are also bound to the same processor 
> ? I am not aware of linux support for binding threads to a CPU so I 
> guess it does not matter .

For a full discussion of this and oter SMP issues, see this article on 
Zope org.

http://www.zope.org/Members/glpb/solaris/multiproc

It is possible to do CPU-affinity on Linux, and nowadyas there are even 
userspace tools that do this.

http://www.hpl.hp.com/research/linux/kernel/o1-openmp.php

http://www.tech9.net/rml/

http://kerneltrap.org/node/view/335


CPU.-affinity is avilable in RH 3.0 per default, and the same tools are 
avialable as a set of patches for various kernel versions.

*In general, on an SMP box, Python processes MUST be bound to any one of 
the CPUs on a amchine* Not the same CPU, but each python process has to 
stay on the same CPU all the time.

As I understand it. the GIL is not a problem *at all* unless you happen 
to run on smp machines. There are ofcourse optimisations to when and 
where to relase the GIL, but in general python takes care of that all by 
itself.

ZEO won't save you from the GIL - ZEO will allow you to scale your Zope 
beyond the constraints of 1 singel zope process for serving the same 
content.

ZEO implements storage of the data Zope serves in one centralised 
location (the ZEO storage server) and allows several Zope processes 
(acting as ZEO clients) to serve/update the same content. These Zope 
processes can ofcourse be placed in a kluster, each ZEO client in a 
different machine.


/dario

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Dario Lopez-Kästen, IT Systems & Services Chalmers University of Tech.