[R] Stopping a function execution automatically after a given time

[Prof Brian Ripley]

On Wed, 2 Apr 2008, Duncan Murdoch wrote:

> On 4/2/2008 12:00 PM, Lukas Rode wrote:
>> Dear Bert and Mel,
>>
>> thanks for your help, but I'm afraid this doesn't solve my problem.
>>
>> As I wrote in my previous mail (cf quote below) in most cases I will not be
>> able to modify the code of the function that I want to run. This is why I
>> was asking for a wrapper solution similar to what tryCatch does. I have
>> hinted at a very inelegant version that generates a new R process for each
>> function run and kills the process after a given time. But I'm sure there
>> must be something more elegant. I hope I have been clear enough in my
>> problem description.
>
> On some systems (not Windows) you could ask some external process to
> send a signal after a certain time interval, and I believe you can write
> you code to recover afterwards.  I don't know any reasonable way to do
> this on Windows.

The problem is that only drastic signals will get listened to, and I don't 
believe they allow you to do anything other than save your work.  SIGKILL, 
SIGTERM, SIGUSR1 and SIGUSR2 are those likely to work (see ?Signals).

Philippe Grosjean said

> You should look at AutoIt or Autohotkey for this.

I don't see how that helps.  R will not respond to keys when running a 
function, including the interrrupt key, unless written to do so.  So on 
Windows if the long-running code is predominantly R (and not compiled C or 
Fortran) and is running from Rgui or interative Rterm (unlikely) then 
pressing ESC/Ctrl-C should interrupt fairly soon.

But almost certainly one is using a batch process.  You can kill that from 
an external process on Windows (but not via SIGUSR1/2, although I think 
that is a non-implementation detail).


I do this by running multiple processes and setting a CPU limit on them 
from the shell used to launch them.  By using 'make -j' I can control how 
many run at once (important on multi-CPU machines).


>
> Duncan Murdoch
>
>>
>> Thanks again,
>>   Lukas
>>
>> Here is what I wrote before:
>> Note that mostly these functions are not written by me and not R code (like
>> nlme for example), so it is not feasible to adapt the function itself.
>> Rather, it needs to be a wrapper around the function, similar to tryCatch.
>>
>>
>>
>> On Wed, Apr 2, 2008 at 5:23 PM, mel <mel at altk.com> wrote:
>>
>>> Lukas Rode a écrit :
>>>
>>>> Nowever, with regard to #2, I am lost. I would like to set a maximum
>>> time
>>>> limit (say, 1 minute) and if my procedure is still running then, I would
>>>> like to move on to the next model.
>>>
>>>
>>> begin_time = as.difftime(format(Sys.time(), '%H:%M:%S'), units='secs');
>>> for(...)
>>>  {
>>>  ...
>>>  current_time = as.difftime(format(Sys.time(), '%H:%M:%S'), units='secs');
>>>  delay = current_time - begin_time;
>>>  if (delay>60) return();
>>>  }
>>>
>>> a counter may also be enough
>>>
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>>
>> 	[[alternative HTML version deleted]]
>>
>>
>>
>> ------------------------------------------------------------------------
>>
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>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
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)
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