[R] how to run R as a daemon

[Prof Brian Ripley]

On Mon, 19 May 2003, Laurent Faisnel wrote:

> Prof Brian Ripley wrote:
> 
> >On Mon, 19 May 2003, Laurent Faisnel wrote:
> >
> >  
> >
> >>I  just visited the link you gave me. One of the problems that could 
> >>occur using NuSOAP is that I do not intend using Python. Thanks anyway. 
> >>I would also like to ask more precise questions :
> >>    
> >>
> >
> >`more precise'?  At least some of the inefficiencies are emerging, but I
> >still have little picture of what you are actually trying to do.  It ought
> >to be possible to run a new R session in a well under a second (on a 1+GHz
> >machine):
> >
> >gannet% time env R_DEFAULT_PACKAGES=NULL R --vanilla --slave < /dev/null
> >0.203u 0.039s 0:00.27 85.1%     0+0k 0+0io 1220pf+0w
> >
> 
> I don't understand how you made this test. What does "gannet%" mean? 

A totally standard Unix prompt: machine_name% is the default prompt in 
csh.

> Anyway, when I launch R with these options (--vanilla and --slave), it 
> is fast enough.
> 
> >
> >for example (on a dual Athlon 2600, R 1.7.0).
> >
> >  
> >
> >>- is it possible to run R as a standalone service, which runs in 
> >>background indefinitely, waiting for instructions ? 
> >>    
> >>
> >
> >It is, but waiting for instructions from one place (stdin or on a socket).
> >
> This is a good piece of news. But how ?
> 
> >There is some danger of different jobs sent leaving things behind that 
> >will cause interactions.
> >
> I 'll make some tests about possible interactions if I successfully 
> launch R in such a mode.
> 
> >>This would be a 
> >>great improvement for me, since each time it is launched R has to 
> >>re-load a (constant) matrix generated thanks to a database connection 
> >>(takes a very long while)
> >>    
> >>
> >
> >You could just save and then load that matrix in your .RData
> >  
> >
> Seems to be a good idea. I'm not used to edit my .RData but sure it 
> would be an improvement. I had not even thought about it.
> 
> >>- my R script is object-oriented; I define classes and methods, but I'm 
> >>not so sure about how methods should be declared; I usually write 
> >>something like :
> >>
> >>mymethod <- function(.Object) UseMethod("mymethod",.Object);
> >>
> >>setMethod("mymethod","myclass",
> >>        function(.Object)
> >>        {
> >>            # instructions
> >>            return(.Object);
> >>        }
> >>        );
> >>
> >>Perhaps is this not the best way to write methods ? Could this explain 
> >>the following fact : when I run the script, R spends about 1/3 of its 
> >>thinking time creating the generic functions linked with my methods. 
> >>Isn't this wasted time ? The same script may be executed many times 
> >>consecutively by different users, and each time R has to re-define the 
> >>generic functions ! (are always the same)
> >>    
> >>
> >
> >Yes, but it is your usage that is the problem.  You are mixing S3 and S4
> >methods (where did you copy an example like that from?).  You should
> >dump your scripts if you use S4 methods (which I don't think you should be
> >doing in such simple examples, nor if you care about speed):  see the
> >examples of S4-using packages on CRAN (e.g. DBI, SparseM).
> >  
> >
> I clearly prefer using S3 classes & methods. I knew S4 classes would 
> cause slowness problems. But I did not find a clear documentation about 
> differences between S3 and S4. Neither did I find detailed tutorials 
> about R programming. Which part of my code structure is S3-like and 
> which one is S4-like ? Is the above-mentionned problem S4 classes' fault 
> ? You mean with clean S3 scripts I would have none of these drawbacks ?

There's a book called `S Programming' that has all this crystal clear, and 
it is in the FAQ!

> >Also consider upgrading to R 1.7.0 and setting R_DEFAULT_PACKAGES to what 
> >you actually need (and omit methods if you don't need it)
> >
> >  
> >
> I won't use R 1.7.0 for the time. First everything has to work fine with 
> R 1.6.2. I think I have few things in R_DEFAULT_PACKAGES, and I cannot 
> omit methods because I use them all !

That's the `methods' package, only needed for S4 methods.

-- 
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)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595