Hi all,
I found some strange behaviour, which I think is a bug. Could someone make an
account for me on Bugzilla or pass on my report?
The problem:
When pressing Ctrl-C when a file is sourced in R, run from Terminal (macOS),
sometimes the entire session is ended right away, while I just want to stop the
script. This is the case when I press Ctrl-C while some functions are running
that don’t catch the interrupt. However, the behaviour is different whether I’m
in a clean session (in which case some time is allowed to pass, so that when
the function returns the script can be interrupted), or whether I have called
base::system() or system2() with timeout other than 0.
Reproducible example:
cat('Start non-interruptable functions\n')
sample_a <- sample(1:1e7)
sample_b <- sample(1:2e7)
matching <- match(sample_a, sample_b)
cat('Finished\n')
Sys.sleep(10)
Observed behaviour:
In a clean session, when I hit Ctrl-C during the execution of match, there is a
delay, and as soon as Sys.sleep() is invoked, the script is interrupted, I get
back my R “>”-prompt (unless options(error=…) is set)
But If I add the line system2("ls", timeout = 5), or something similar, when I
try to break during the first part of the script, my Rsession ends, I get
thrown back to my terminal-prompt.
Desired behaviour:
The best setup would probably be if Ctrl-C would always try to break from the
sourced file, and only if that doesn’t success in n seconds, break the rsession
altogether, ideally with a customizable option. But maybe that’s too hard, so
maybe the most pragmatic would be to have 2 hotkeys: one to break from a
hanging/broken rsession, and one to gently try to break from a script. But at
least I think it should be:
Expected behaviour:
Consistent behaviour for Ctrl-C: either trying to break the script, or end the
session altogether.
Some observations:
* I can still break cleanly during the Sys.sleep(). But for larger scripts,
it is largely a matter of luck if I hit Ctrl-C during the right moment.
* I don’t notice any difference between using system or system2, or any of
the arguments other than timeout provided
* I don’t notice any difference whether the timeout is actually exhausted
or not.
* Later calls to system/system2 don’t change anything (i.e. later calling
system(…, timeout=0) does not revert back to the old situation)
My setup:
R 3.5.1 (Feather Spray), run with –vanilla option
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin17)
macOS High Sierra 10.13.6
Best regards,
Emil Bode
Data-analyst
+31 6 43 83 89 33
emil.b...@dans.knaw.nl<mailto:emil.b...@dans.knaw.nl>
DANS: Netherlands Institute for Permanent Access to Digital Research Resources
Anna van Saksenlaan 51 | 2593 HW Den Haag | +31 70 349 44 50 |
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