[R] makeSOCKcluster

[Prof Brian Ripley]

On Fri, 1 Sep 2006, Hrishikesh Rajpathak wrote:

> Hi,
>   
>   I am a newbie to R and trying to implement parallelism in R. I am 
>   currently using R-2.3.1, and Cygwin to run R on Windows xp.

Did you build R under Cygwin (which is not a supported platform), or are 
you running a native Windows build of R?  If the latter, you may be being 
optimistic to expect R to run Unix commands in the same way as under Unix.

I presume you mean this line in package snow:

    system(paste(rshcmd, "-l", user, machine, "env", env, script))
 
which appears to be attempting to run a shell script: no shell is used by 
system() on Windows R.  As the return value is not checked, this will not 
fail.

R under Windows differs from R under Unix in a number of ways, and 
system() is a major one.


>   ssh and all are working fine,
>   
>   When I try to create a socket connection as
>   
>    makeSOCKcluster(c("localhost","localhost")), 
>   
>   it just waits for the other prcess on localhost to get created and respond. But this other process is not created.
>   
>   To debug, I put print statements in the "snow " file in library\snow\r  of R after every statement that comes under Socket Implementation. I  realized that it does the execution till
>   
>   system(a<-paste(rshcmd, "-l", user, machine, "env", env, script))
>   
>   part and then it goes in wait state. It cannot run the next command which is
>   
>   con <- socketConnection(port = port, server=TRUE, blocking=TRUE,
>                                open="a+b")
>   
>   can someone please tell me what exactly could be the problem?
>   
>   Thank you,
>   Rishi

-- 
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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