On Linux, at least, you can have various processes write into the same file, by
opening
it with "r+" mode and calling seek() to position the file pointer before
writing. E.g.,
> library(parallel)
> cl4 <- makeCluster(4)
> tf <- tempfile()
> cat(rep("--------", 2*length(cl4)), sep="\n", file=tf)
> readLines(tf)
[1] "--------" "--------" "--------" "--------" "--------" "--------" "--------"
[8] "--------"
> z <- parLapply(cl4, 8:1, function(i, tf){
f <- file(tf, open="r+")
on.exit(close(f))
seek(f, (i-1)*9, rw="w")
ret <- c(i, Sys.getpid())
cat(ret, file=f); ret},
tf=tf)
> readLines(tf)
[1] "1 22406-" "2 22406-" "3 22397-" "4 22397-" "5 22388-" "6 22388-" "7 22379-"
[8] "8 22379-"
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> Of Jeff Newmiller
> Sent: Wednesday, October 30, 2013 12:58 PM
> To: Zhifa Liu; r-help@r-project.org
> Subject: Re: [R] multiple concurrent write in R
>
> I think the answer is no. Use the master process to manage IO.
> ---------------------------------------------------------------------------
> Jeff Newmiller The ..... ..... Go Live...
> DCN:<jdnew...@dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go...
> Live: OO#.. Dead: OO#.. Playing
> Research Engineer (Solar/Batteries O.O#. #.O#. with
> /Software/Embedded Controllers) .OO#. .OO#. rocks...1k
> ---------------------------------------------------------------------------
> Sent from my phone. Please excuse my brevity.
>
> Zhifa Liu <zhifa...@gmail.com> wrote:
> >I have over 200 CPUs could write to the same file at the same time,
> >does
> >someone know how to handle the multiple concurrent write in R?
> >
> > [[alternative HTML version deleted]]
> >
> >______________________________________________
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> >PLEASE do read the posting guide
> >http://www.R-project.org/posting-guide.html
> >and provide commented, minimal, self-contained, reproducible code.
>
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