[R] Parallel computing on Windows (foreach)

[R. Michael Weylandt]

It's sad, but not an impossible result with synchronization overhead
(though I wouldn't have guessed it would be that bad) -- can you try
it on a more reasonable benchmark?

Also, that advice might be somewhat out of date -- why not use the
tools provided in

 library(parallel)

available for recent versions of R?

Michael

On Thu, Jul 26, 2012 at 8:00 AM, deep123 <deps_123 at yahoo.co.in> wrote:
> Hello all,
> My problem is similar to Sergey's.
> I could not try what Mario suggested, since doMPI is not available for
> windows.
>
> I have tried the Cedrick's commands, i.e.
> cl.tmp = makeCluster(rep("localhost",2), type="SOCK")
> registerDoSNOW(cl.tmp)
>
> but this is instead increasing the time taken. For Sergy's set of commands,
> i get,
>> x <- numeric(10000)
>> system.time(for(i in 1:10000) x[i] <- sqrt(i))
>    user  system elapsed
>    0.03    0.00    0.03
>> system.time(system.time(x <- foreach(i=1:10000, .combine="c") %do%
>> sqrt(i)))
>    user  system elapsed
>    4.71    0.00    4.71
>> system.time(system.time(x <- foreach(i=1:10000, .combine="c") %dopar%
>> sqrt(i)))
>    user  system elapsed
>    7.35    1.07  127.06
>
> i.e. %dopar% is taking longer than %do%
>
> Please guide me.
>
>
>
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