[R-SIG-Mac] How to interrupt an R process that hangs

[Matthew Keller]

Hi all,

Thanks Simon and Duncan for the help. Sorry to be dense, but I'm still
unsure how to interrupt such processes. Here's an example:

for (i in 1:100000){
	a <- matrix(rnorm(100000*100000),ncol=100000)
	b <- svd(a)	}

If you run this, R will hang (i.e., it's a legitimate execution, it
will just take a really long time to execute). The most obvious
solution is to write code that doesn't do unintended things, but
that's not always possible. Is there a way to interrupt it? I tried:

kill -s INT <PID>

and at least on Mac it had no effect. Thanks again,

Matt



On Mon, Mar 15, 2010 at 1:19 PM, Simon Urbanek
<simon.urbanek at r-project.org> wrote:
>
> On Mar 15, 2010, at 14:42 , Adam D. I. Kramer wrote:
>
>> +1--this is the single most-annoying issue with R that I know of.
>>
>> My usual solution, after accomplishing nothing as R spins idly for a
>> couple
>> hours, is to kill the process and lose any un-saved work.  save.history()
>> is
>> my friend, but is a big delay when you work with big data sets as I do, so
>> I
>> don't run it after every command.
>>
>> I have cc'd r-help here, however, because I experience this problem with
>> non-OSX R as well...when I run it in Linux or from the OSX command-line (I
>> compile R for Darwin without aqua/R-framework), the same thing happens.
>>
>> Is there some way around this? Is this a known problem?
>>
>
> "Hanging" for a long period of time is usually caused by poorly written
> C/Fortran code. You can always interrupt R as long as it is in the R code.
> Once you load a package that uses native code (C/Fortran/..) you have to
> rely on the sanity of the developer to call R_CheckUserInterrupt() or
> rchkusr() often enough (see 6.12 in R-ext). If you have some particular
> package that does not do that, I would suggest alerting the author. By
> definition this requires cooperation from authors, because interrupting
> random code forcefully (as it was possible many years ago) creates leaks and
> unstable states.
>
> Cheers,
> Simon
>
>
>
>> Google searching suggests no solution, timeline, or anything, but the
>> problem has been annoying users for at least twelve years:
>> http://tolstoy.newcastle.edu.au/R/help/9704/0151.html
>>
>> Cordially,
>> Adam
>>
>> On Mon, 15 Mar 2010, Matthew Keller wrote:
>>
>>> HI all,
>>>
>>> Apologies for this question. I'm sure it's been asked many times, but
>>> despite 20 minutes of looking, I can't find the answer. I never use
>>> the GUI, I use emacs, but my postdoc does, so I don't know what to
>>> tell her about the following:
>>>
>>> Occasionally she'll mess up in her code and cause R to hang
>>> indefinitely (e.g., R is trying to do something that will take days).
>>> In these situations, is there an option other than killing R (and the
>>> work you've done on your script to that point)?
>>>
>>> Thank you,
>>>
>>> Matthew Keller
>>>
>>>
>>> --
>>> Matthew C Keller
>>> Asst. Professor of Psychology
>>> University of Colorado at Boulder
>>> www.matthewckeller.com
>>>
>>> _______________________________________________
>>> R-SIG-Mac mailing list
>>> R-SIG-Mac at stat.math.ethz.ch
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>>>
>>
>> _______________________________________________
>> R-SIG-Mac mailing list
>> R-SIG-Mac at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>>
>>
>
>



-- 
Matthew C Keller
Asst. Professor of Psychology
University of Colorado at Boulder
www.matthewckeller.com