[dundee] Rails work

[Barry Carr]

Lee Hughes wrote:
> 
> 
> */Gary Short <gary at garyshort.org>/* wrote:
> 
>     -------- Original Message --------
>      > From: Lee Hughes
>      > Sent: 11 February 2008 13:28
>      > To: Tayside Linux User Group
>      > Subject: Re: [dundee] Rails work
>      >
>      > Can't you just load balance with a farm? I've load balanced a few
>     php apps
>      > before, with success? or is there something with rails I'm missing?
>      > does it support database locking for example?
> 
>     The trouble with Rails is that it uses the MVC pattern (Model, View
>     Controller) where the interaction between the Model (an object that
>     holds entity information and has business behavour) and the View
>     (the web page in this case) is managed by the Controller.
> 
>     So, you may see a URL like http://www.MyDomain.com/customer/12/edit
>     (which means edit the customer who has id = 12). However, this URL
>     doesn't actually exist and Mod_rewrite is used to route the request
>     to http://www.MyDomain.com/controllers/customer.rb (or similar)
>     passing /customer/12/edit as a parameter so that the code in the
>     controller knows what to do. This is really cool BTW, but makes load
>     balancing a PITA.
> 
>     This is not a problem confined to Rails of course, all MVC
>     frameworks (Rails, ASP.Net MVC, CakePHP etc) have this problem to
>     overcome. However, Rails further suffers from Ruby's inherent poor
>     performance aswell. Look out for this being fixed in the short to
>     medium term though, very clever people are working on it right now.
> 
>     -- 
>     Cheers,
>     Gary
>     http://www.garyshort.org
> 
> 
> Very Interesting, so, I guess the only open is to balance on source ip 
> address
> of the client, and direct same request to the same server , not exactly 
> dynamic
> balancing but it will work. However, sharing session state was always a
> big problem, store it in memory (of the web server) and you have a problem
> distributing that across the cluster, store it in the database and you have
> the problem of performance , you have to reread you session variables on 
> every
> page load. . pick yer enemy.
> 
> Keeping clients on the same server seems to do the job, but it's always
> better if a farm of servers can handle any request, ensuring the least 
> loaded
> get works to do.
> 
> Does rails have any caching , like  mmcache?
> 
> that would certainly speed things up, why recompute a web page, when
> 9 times out of 10, your serving dynamic (which does'nt change that much).
> 
> It's certainly interesting stuff, from now on I'm moving from rails to
> assembler code. that should improve performance somewhat ;-)
> 
It is possible to get apache to help with load balancing. Basically you configure apache to hive off 
an incoming request to a mongrel instance. The server will be running several mongrel instances 
(hence the term "a pack of mongrels"). Another option open to you (and I know even less about this) 
is use JRuby and Glassfish v2.0. As I understand it this is supposed to have reasonable performance. 
Glassfish is open source and you can get it with Netbeans 6.0 (www.netbeans.org)

HTH

Cheers
Barry