Unfortunately --interactive also makes the session interactive(), which is bad for me, as it is a background session.
In general, I don't want the interactive behavior, but was wondering if I could send as SIGINT to try to interrupt the computation of the background process, and if that does not work, then I would send a SIGKILL and start up another process. It all works nicely, except for this glitch, but I think I can work around it. Thanks, Gabor On Tue, Apr 30, 2019 at 10:55 PM Tierney, Luke <luke-tier...@uiowa.edu> wrote: > > A Simon pointed out the interrupt is recorded but not processed until > a safe point. > > When reading from a fifo or pipe R runs non-interactive, which means > is sits in a read() system call and the interrupt isn't seen until > sometime during evaluation when a safe checkpoint is reached. > > When reading from a terminal R will use select() to wait for input and > periodically wake and check for interrupts. In that case the interrupt > will probably be seen sooner. > > If the interactive behavior is what you want you can add --interactive > to the arguments used to start R. > > Best, > > luke > > On Tue, 30 Apr 2019, Gábor Csárdi wrote: > > > OK, I managed to create an example without callr, but it is still > > somewhat cumbersome. Anyway, here it is. > > > > Terminal 1: > > mkfifo fif > > R --no-readline --slave --no-save --no-restore < fif > > > > Terminal 2: > > cat > fif > > Sys.getpid() > > > > This will make Terminal 1 print the pid of the R process, so we can > > send a SIGINT: > > > > Terminal 3: > > kill -INT pid > > > > The R process is of course still running happily. > > > > Terminal 2 again: > > tryCatch(Sys.sleep(10), interrupt = function(e) e) > > > > and then Terminal 1 prints the interrupt condition: > > <interrupt: > > > > > This is macOS and 3.5.3, although I don't think it matters much. > > > > Thanks much! > > G. > > > > On Tue, Apr 30, 2019 at 9:50 PM Simon Urbanek > > <simon.urba...@r-project.org> wrote: > >> > >> Can you give an example without callr? The key is how is the process > >> stated and what it is doing which is entirely opaque in callr. > >> > >> Windows doesn't have signals, so the process there is entirely different. > >> Most of the WIN32 processing is event-based. > >> > >> Cheers, > >> Simon > >> > >> > >>> On Apr 30, 2019, at 4:17 PM, Gábor Csárdi <csardi.ga...@gmail.com> wrote: > >>> > >>> Yeah, I get that they are async. > >>> > >>> What happens is that the background process is not doing anything when > >>> the process gets a SIGINT. I.e. the background process is just > >>> listening on its standard input. > >>> > >>> AFAICT for an interactive process such a SIGINT is just swallowed, > >>> with a newline outputted to the terminal. > >>> > >>> But apparently, for this background process, it is not swallowed, and > >>> it is triggered later. FWIW it does not happen on Windows, not very > >>> surprisingly. > >>> > >>> Gabor > >>> > >>> On Tue, Apr 30, 2019 at 9:13 PM Simon Urbanek > >>> <simon.urba...@r-project.org> wrote: > >>>> > >>>> Interrupts are not synchronous in R - the signal only flags the request > >>>> for interruption. Nothing actually happens until R_CheckUserInterrupt() > >>>> is called at an interruptible point. In you case your code is apparently > >>>> not calling R_CheckUserInterrupt() until later as a side-effect of the > >>>> next evaluation. > >>>> > >>>> Cheers, > >>>> Simon > >>>> > >>>> > >>>>> On Apr 30, 2019, at 3:44 PM, Gábor Csárdi <csardi.ga...@gmail.com> > >>>>> wrote: > >>>>> > >>>>> Hi All, > >>>>> > >>>>> I realize that this is not a really nice reprex, but anyone has an > >>>>> idea why a background R session would "remember" an interrupt (SIGINT) > >>>>> on Unix? > >>>>> > >>>>> rs <- callr::r_session$new() > >>>>> rs$interrupt() # just sends a SIGINT > >>>>> #> [1] TRUE > >>>>> > >>>>> rs$run(function() 1+1) > >>>>> #> Error: interrupt > >>>>> > >>>>> rs$run(function() 1+1) > >>>>> #> [1] 2 > >>>>> > >>>>> It seems that the main loop somehow stores the SIGINT it receives > >>>>> while it is waiting on stdin, and then it triggers it when some input > >>>>> comes in.... Maybe. Just speculating.... > >>>>> > >>>>> Thanks, > >>>>> Gabor > >>>>> > >>>>> ______________________________________________ > >>>>> R-devel@r-project.org mailing list > >>>>> https://stat.ethz.ch/mailman/listinfo/r-devel > >>>>> > >>>> > >>> > >> > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > -- > Luke Tierney > Ralph E. Wareham Professor of Mathematical Sciences > University of Iowa Phone: 319-335-3386 > Department of Statistics and Fax: 319-335-3017 > Actuarial Science > 241 Schaeffer Hall email: luke-tier...@uiowa.edu > Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
