[Swift-devel] Coaster capabilities for release 0.9

[Mihael Hategan]

On Wed, 2009-04-22 at 10:49 -0500, Ian Foster wrote:
> > > > 
> > > > 
> > > > What you say does beg for a couple of questions:
> > > > - if all work is done in a run but the allocation has more time
> > > > left,
> > > > should the workers be shut down or not?
> 
> 
> Shut down.

Ok.

> 
> > > > 
> > > > - if more work remains to be done in a run after an explicit  
> > > > allocation
> > > > was used, should the system attempt to allocate more nodes? If
> > > > not,
> > > > should it hang? Fail?
> 
> 
> Fail.

I disagree. If the user didn't want the work to complete, they wouldn't
run it. It should be possible to force this mode, but I don't think it
should be the default.

> 
> > > > 
> > > > - if the allocation is far in the distance from now, and a run
> > > > is
> > > > started now, is allocating nodes now a matter of second-guessing
> > > > or a
> > > > matter of trying to finish the work faster? What, besides
> > > > alleged
> > > > complexity of the algorithm, would be the downside of doing so?
> 
> 
> Maybe someone has requested an allocation at 10am tomorrow because
> that is when they want to run the application.

I'd assume then that they would start swift somewhere around 10am
tomorrow, not one or two days in advance.

> 
> 
> Maybe they are benchmarking, and want things to run with a specified
> number of nodes).
> 

Being able to force a "use exactly these nodes for this amount of time
at this time" is a given. Making it the default I have issue with.

> 
> Maybe someone doesn't trust the clever algorithm, or finds that it
> fails for odd reason.
> 

Right. Many people don't trust garbage collection either. I find it
funny that people insist that non-trivial things such as distributed
computing, GC, special relativity be entirely intuitive.

> 
> Having a more complex algorithm as well is great. I'm not saying this
> would not be wonderful. But it shouldn't be obligatory.

That's far from the statement of making the other one the default.

Let's ask our users though!