Skip to content

can R scripts detect signals sent by the task scheduler ?

6 messages · mauede at alice.it, Barry Rowlingson, Dirk Eddelbuettel +1 more

Barry Rowlingson
#
On Fri, Nov 20, 2009 at 1:25 PM, <mauede at alice.it> wrote:
Yes, the only problem might be if you use anything that needs a
graphics window. In the old days you needed an X11 display to create
png graphics with the png() function, but not any more. I'm not sure
if yo need an X11 system for anything apart from showing graphs. But I
don't know everything.
?Signals:

Interrupting Execution of R
Description:
     On receiving ?SIGUSR1? R will save the workspace and quit.
     ?SIGUSR2? has the same result except that the ?.Last? function and
     ?on.exit? expressions will not be called.

 So if you can send that signal to your process you might be in luck.
However if by 'system interrupt' you mean the SIGQUIT signal, then I'm
not sure that R can trap interrupts to that extent. You might want to
see if your operating system supports 'checkpointing', in which case
any process can be saved and restarted.

 If by 'system interrupt' you mean SIGKILL (signal 9) then you are very stuck.

 What is going on in your system? Are you trying to checkpoint if the
machine is shut down?

 Barry
Dirk Eddelbuettel
#
On 20 November 2009 at 14:25, mauede at alice.it wrote:
| In general, is it possible to run R scripts through cron jobs ?
| Is it possible to make  the script detect the system interrupt, save its current status and then exit so that next time it is rescheduled it can pick up from where it left ? 
| Examples, if any, are more then welcome.

You are conflating a few things here:

  i)    yes, you can run R from cron or task scheduler -- that is how R
        updates webpages on the R site, how CRANberries is updated etc pp
 
  ii)   to a program, it doesn't matter who started it, be it the task
        scheduler or interactive use (modulo correcly setup PATH et al
        variables

  iii)  R and its predecessor systems have stopped and resumed for decades,
        look at help(save.image) or help(save)

  iv)   Snapshotting running applications and resuming them elsewhere is
        an operating system task -- some OSs do this, but typically not
        in consumer grade versions.

Hope this helps, Dirk
Brian Ripley
#
On Fri, 20 Nov 2009, Barry Rowlingson wrote:

            

      
      
      
    

        
Some package authors assume such a display to install their packages 
(and a few of those may not have a choice as some graphics libraries 
seem to need one to be loaded). So my dept's automated package updater 
scripts run from cron, and start (and stop) a Xvfb X server to get 
around that.

[...]

  
    

      
      
    

  


  


      

    

    

      
      

        
      

    

    

      
      

        


  

        

      Barry Rowlingson
    

    

      
      #
    

  


  

      
On Fri, Nov 20, 2009 at 11:01 PM,  <mauede at alice.it> wrote:

            

      
      
      
    

        
I suspect there's no such thing for Windows. Process control and
signalling is something very different between operating systems, so
someone needs to write a dedicated Windows version of that package.

 See here:

http://ftp.heanet.ie/mirrors/cran.r-project.org/web/packages/fork/index.html

Barry