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Re: Parallel Haskell Digest 5


Kevin Hammond Sep 5, 2011 3:22 AM
Posted in group: parallel-haskell
Hi Andres,

On 5 Sep 2011, at 11:36, Andres Löh wrote:

>> I'm saying that, from a pedagogical perspective, the first version is a bad example to begin with, and that it's better to show the separated version from the start
>> (this also leads into the development/use of parList rseq [or probably rdeepseq]).  My experience is that people copy examples...
>
> Ah, ok, fair enough. There's always a risk, I agree. I think the
> presentation as given was inspired by the fact that the previous
> digest covered par/pseq in isolation, and we wanted to move from there
> to more advanced concepts step by step.

I'm saying that the separate strategy is the next step :)

>> We have been hitting some performance debugging issues - I'm pinging Simon independently about these - we really want this to be as easy to use
>> as possible.
>
> So do we :) We'd probably be interested hearing about your performance
> debugging issues, too, as we're still busy improving ThreadScope ...


I'll pass this on once I've worked out the technical details - in some cases we've rewritten code so that it works, but we only have an intuition why.
One thing that would be immediately useful would be a spark profile (as I know is coming in the next release).  The ThreadScope profiles can also hide detail
(e.g. appear to show parallelism when this is actually subsumed by GC).

Best Wishes,
Kevin

--------

Kevin Hammond, Professor of Computer Science, University of St Andrews

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