[Seaside] Concurrency question

[James Foster]

Hi Jeffrey,

Welcome to Seaside!

You are right that most implementations of Smalltalk are single- 
threaded. There is, however, a built-in process scheduler ("green  
threads") that allows code to be forked. If your long-running request  
is compute bound and you reduce its priority or yield periodically  
then other requests should be handled. If your long-running request is  
waiting on an external resource (the typical example is credit card  
verification), you might be able to code things so that that  
particular request is in a separate OS thread or takes advantage of a  
non-blocking socket wait. I believe that these comments apply to  
Squeak's implementation of Seaside (and possibly the VW implementation  
as well).

In GemStone each VM is also single-threaded but you can have multiple  
VMs attached to the same object space. Here the typical approach is to  
use Apache to round-robin requests to separate VMs so that blocking is  
less of an issue. See http://seaside.gemstone.com and http://gemstonesoup.wordpress.com 
  for more info.

James


On Feb 17, 2008, at 12:00 PM, Jeffrey Straszheim wrote:

> Howdy folks,
>
> I'm currently evaluating Seaside for a project and have a question.   
> How does it handle concurrent connections?  I understand that the  
> underlying Squeak VM does not use OS threading, and so the system  
> does not take advantage of SMP.  That is OK with me.  However, I'm  
> curious if Seaside will still be able to handle the situation where  
> we get one or more LONG http requests.  Will these cause undo lag to  
> other users trying to connect.
>
> To give some background for my concern, I've been using Rails, which  
> is strictly single threaded, so a long response to a single request  
> can cause other users to be blocked out from that rails instance.   
> I'm hoping Seaside will not have this problem.
>
> Thanks in advance,
>
> Jeffrey Straszheim
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