[R] Fwd: Issue with mcapply

[AROONALOK PYNE]

---------- Forwarded message ----------
From: AROONALOK PYNE <aroonalok.pyne at gmail.com>
Date: Thu, Jun 11, 2015 at 2:25 PM
Subject: Re: Issue with mcapply
To: Rainer M Krug <Rainer at krugs.de>


R version 3.0.2 (2013-09-25)


Large value : 9999999


I rerun the code as c(10000000) for which your machine works fine but
my code still hangs on reaching b(). I am running it from Linux
Terminal.


On Thu, Jun 11, 2015 at 2:15 PM, Rainer M Krug <Rainer at krugs.de> wrote:

> AROONALOK PYNE <aroonalok.pyne at gmail.com> writes:
>
> > Please check this code :
> >
> > library(parallel)
> > workerFunc <- function(n) { return(n^2) }
> > a <- function(){
> >   CurrentTime <- Sys.time()
> >   res <- lapply(values, workerFunc)
> >   TimeTaken <- Sys.time() - CurrentTime
> >   print(TimeTaken)
> > }
> > b <- function(){
> >   CurrentTime <- Sys.time()
> >   numWorkers <- detectCores()
> >   res <- mclapply(values, workerFunc, mc.cores = numWorkers-2)
> >   TimeTaken <- Sys.time() - CurrentTime
> >   print(TimeTaken)
> > }
> > c <- function(n){
> >   values <<- 1:n
> >   print("Evaluating a : ")
> >   a()
> >   print("Evaluating b : ")
> >   b()
> > }
> >
> > For large values of n, the code calculates a() but the hangs indefinitely
> > on reaching b(). How do I correct it ?
> > I am using Ubuntu 14.04 and core i7 Processor
>
> Which version of R and what are "large values"?
>
> I just did the following successfully:
>
> ,----
> | > c(100)
> | [1] "Evaluating a : "
> | Time difference of 0.0002059937 secs
> | [1] "Evaluating b : "
> | Time difference of 0.02037406 secs
> | > c(1000)
> | [1] "Evaluating a : "
> | Time difference of 0.001929998 secs
> | [1] "Evaluating b : "
> | Time difference of 0.01943302 secs
> | > c(1000000)
> | [1] "Evaluating a : "
> | Time difference of 1.822959 secs
> | [1] "Evaluating b : "
> | Time difference of 1.46111 secs
> | > c(10000000)
> | [1] "Evaluating a : "
> | Time difference of 23.55863 secs
> | [1] "Evaluating b : "
> | Time difference of 15.90938 secs
> | >
> `----
>
> Cheers,
>
> Rainer
> --
> Rainer M. Krug
> email: Rainer<at>krugs<dot>de
> PGP: 0x0F52F982
>



-- 
*AROONALOK PYNE*

BE Graduate
Department Of Computer Science And Engineering
Jadavpur University, Kolkata-32
India





-- 
*AROONALOK PYNE*

BE Graduate
Department Of Computer Science And Engineering
Jadavpur University, Kolkata-32
India

	[[alternative HTML version deleted]]