[Seaside] Re: Which persistence solution to use?

[Philippe Marschall]

2007/5/13, James Foster <Smalltalk at jgfoster.net>:
> On Sunday 13 May 2007 8:52 am, Philippe Marschall wrote:
> > 2007/5/13, James Foster <Smalltalk at jgfoster.net>:
> > > On Sunday 13 May 2007 2:43 am, Udo Schneider wrote:
> > > > James Foster wrote:
> > > > > Why "outside the image"? Do you need to get access to the data from
> > > > > something other than Seaside?
> > > >
> > > > Not really. The reason is to be able to share the data between multiple
> > > > running Squeak/Seaside instances.
> > >
> > > Why do you need multiple instances? Is one instance unable to handle the
> > > requests?
> >
> > Scaling, computer with more than one CPU/core, failover, ....
> >
> > Cheers
> > Philippe
>
> Hi Philippe,
>
> Are you answering on behalf of Udo, or are you just providing a general list
> of reasons why someone might want to run multiple instances?

The later. Besides that Squeak Images can get from time to time in a
state ... how shall I put that whithout using the f-word?
- They can lock up for no particular reason (either at 100% or 0% CPU usage)
- They can lock up or crash because of memory/garbage collection problems
- The ui process can lock up for no particular reason
- WeakArray finalization can happen can block the image for 20 minutes
- Semaphore >> #cirtical: might not exit (although the block is finished)
- low space signals (again with ImageSegments)
- you name it

> Are you making a
> distinction between "scaling" and "computer with more than one CPU/core" or
> are the two reasons equivalent?

Doesn't really matter for Squeak.

> How many pages per second are your serving
> such that one instance is inadequate?

It's interesting already earlier. As soon as you have an incoming
request when an old one isn't already answered and you have free
processing power (a cpu or core) you can use this to answer it faster
and increase the responsiveness of your application.

Cheers
Philippe

> James
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