R devel - Oct 2011 - parallel::mclapply() dummy function on Windows?

Hi all,

Would it be possible to have the new 'parallel' library export a dummy
function, something akin to

if(Windows) mclapply <- lapply

to paper over the lack of fork() support on said platform?  This may not be
the world's greatest idea, but it would make it easier for me to maintain my
package and still offer most users good parallel support.  Plus, I can't
really see where it would cause problems, but then I don't develop R,
myself.

Thanks for any thoughts on the matter.


-- 
If people do not believe that mathematics is simple,
it is only because they do not realize how complicated life is. John von
Neumann<http://www-groups.dcs.st-and.ac.uk/~history/Biographies/Von_Neumann.html>

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On Thu, 6 Oct 2011, Tim Triche, Jr. wrote:
> Hi all,
>
> Would it be possible to have the new 'parallel' library export a
dummy
> function, something akin to
>
> if(Windows) mclapply <- lapply
>
> to paper over the lack of fork() support on said platform?  This may not be
> the world's greatest idea, but it would make it easier for me to
maintain my
> package and still offer most users good parallel support.  Plus, I
can't
Why would it make it easier?  And how could using a dummy for 'most 
users' (who are on Windows) offer them 'good parallel support'?
> really see where it would cause problems, but then I don't develop R,
> myself.
Take a look at e.g. package 'boot' to see how to offer alternatives. 
(A version that uses 'parallel' is pending on CRAN, or see 
http://www.stats.ox.ac.uk/pub/R/boot_1.3-3.tar.gz .) Package 
'parallel' may in future offer a higher-level abstraction layer that 
makes offers such a choice, but as the 'boot' code shows, deciding 
what to send to the workers in a snow-style cluster is not simple.

Note that it is not just Windows that lacks fork support: some 
front-ends (notably Rstudio) do not work with forking at present. And 
some parts of parallel (and multicore/snow) do not work reliably on 
some OSes (e.g. Solaris).
> Thanks for any thoughts on the matter.
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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