[plt-dev] Parallel Futures Release

From: Ryan Culpepper (ryanc at ccs.neu.edu)
Date: Mon Dec 7 14:36:05 EST 2009

Congratulations on your initial release!

My question: How do futures relate to the existing constructs, such as  
thread-local cells, parameters, and custodians? (Eli raised some  
questions about the last one. It would be nice to fit futures  
gracefully into the existing framework.)

It would be nice if futures could be though of as similar to threads  
but with special scheduling. For example, if

   (let ([f (future (lambda () E1))])
     (touch f))


   (let* ([chan (make-channel)]
          [t (thread (lambda () (channel-put chan E1)))])
     (channel-get chan))

with respect to thread-local state, shut-down-ability, etc. Or if they  
need to be different, I'm curious why.


On Dec 7, 2009, at 12:31 PM, James Swaine wrote:

> I'm pleased to announce the initial release of parallel futures, a
> construct for fine-grained parallelism in PLT. Roughly speaking, a
> programmer passes a thunk to 'future' and it gets run in parallel.
> That "roughly" holds a few gotchas, partly because we're just getting
> started and partly due to the technique we're using. See the
> documentation for more details:
>  http://pre.plt-scheme.org/docs/html/futures/
> If you've got a multicore machine where you can't keep the cores busy
> or your office/machine room is a bit cold, try this program:
> #lang scheme
> (require scheme/futures)
> (define (loop) (loop))
> (for-each
>  touch
>  (for/list ([i (in-range 0 (processor-count))])
>   (future loop)))
> Note that you have to build mzscheme with futures; it isn't enabled by
> default, but see the docs above for how to do that. Beyond the above,
> we've also gotten a few parallel kernels going and are seeing good
> scalability up to 8 cores (the biggest machine we have around for the
> time being).
> Many thanks to Matthew, Robby, Kevin, and Peter Dinda, without whom  
> this
> release wouldn't have been possible.
> Feedback welcome!
> James _________________________________________________
>  For list-related administrative tasks:
>  http://list.cs.brown.edu/mailman/listinfo/plt-dev

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