Ramiro Diaz Trepat wrote:
> Cees, my point is not mooted.  Most web applications use threading. 
> Most of the servers that run our applications today are Dual Opterons
> running Linux.
> Nobody yet answered why they think it's all right to have to do
> Processor yields in your code for threads of same priority.
> Are you really that conservative, I mean to defend teeth and claws
> anachronic green threads?
> Wouldn't you be happy with a preemtive system that worked fine?  Not
> having to do fake load balancing haviing different images doing
> different jobs? Not having to ever write Processor yield?
> come on... what would be wrong with native threads?

Ramiro,

My web site runs two web applications written in Squeak. Both of them 
are multi-threaded, and neither of them calls #yield. It runs on a 
multi-processor box, along with apache, DNS and mail servers, and under 
load none of the processors is wasted. I'm quite happy with this system. 
It's preemptive and works fine.

Here's what would be wrong with native threads:

- They would be less efficient than Squeak Processes. A Process is very 
lightweight, and context switches in Squeak are very cheap. A context 
switch using native threads is very expensive by comparison.

- They would be less scalable than Squeak Processes. Squeak can run 10K 
Processes in an image with ease. You just can't do that with native threads

- They wouldn't run identically on all platforms. A single Squeak image 
runs identically on all the platforms, and that includes directly on the 
hardware, without an OS. With native threads, you can approximately the 
same behaviour, on some platforms.

- Using native threads makes garbage collection really difficult, 
particularly if you want to minimize pauses. Given that Squeak is 
commonly used in multimedia applications, where GC pauses interfere with 
smooth audio processing and animation, native threads would be problematic.

So, given that what we have today works fine for any practical need, and 
that moving to native threads would take away capabilities that we 
currently have, I see no reason to do it.

This is my last post on this topic. If you are truly interested using 
Squeak for your business I'll be happy to talk about how to do that.

Colin