Way to make R idle for some time and try something again later

This depends on what else is going on.  My guess is that you are 
running the Aqua GUI, and it is servicing the GUI which is taking 
the time, not R itself.

On all of Linux, Solaris and Windows (RGui or Rterm) Sys.sleep() 
does use very close to zero resources at the beginning of a session, 
but things may be different if e.g. tcltk widgets are in use.

On Fri, 29 Jul 2005, Don MacQueen wrote:

I done something very similar -- have R watch a file, and whenever
new data is added to the file, read the new data from the file. In my
case, new data was arriving once per minute, so I needed to have R
wait about a minute before looking for new data.

On my unix-based system, I found that if I usd

I don't think your system IS `unix-based' (Unix is a trademark, and 
MacOS X is based on a rather different kernel).  It is quite 
possible that it is behaving differently from the POSIX description 
of Unix system calls on which R is based for Unix-alikes.

      Sys.sleep( N )
then cpu usage immediately went up drastically. If the the system is
otherwise fairly idle, cpu usage goes up to nearly 100%. A cpu
monitor shows that R is using the cpu cycles.

If I use instead
     system('sleep N')
cpu usage does not go up.

Does that freeze the GUI?  It certainly freezes tcltk widgets on Unix.

(where N is the number of seconds to sleep)

 version

         _
platform powerpc-apple-darwin7.9.0
arch     powerpc
os       darwin7.9.0
system   powerpc, darwin7.9.0
status
major    2
minor    1.1
year     2005
month    06
day      20
language R


At 12:13 PM -0700 7/29/05, Tae-Hoon Chung wrote:

Hi, All;

I have a question. In R, what is the best way to make R idle for a while and
try something again later? For example, suppose there is an R job which
accesses a file that may be shared with other active jobs. So when the file
is being accessed by other job, your job will not be able to access the file
and your job will crash because of that. To avoid this, you want your job to
try to access the file repeatedly with some time interval, say every 10
seconds or something like that. Which is the best way to do this in R?

--
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