Thank you for the elaborate response. I am going to look into the quartz code.
> On top of my head I can't think of a built-in solution in R at this point
> (even though it could be argued that R might install a handler itself when
> the limit is set ...).
Yes, I think this would greatly enhance the usability of setTimeLimit.
> But note that this is really just a special case of of Sys.sleep(). If you
> actually run R code, then ProcessEvents is triggered automatically during the
> evaluation (or in interruptible C code).
Well, the main use case that I have in mind is where the process is
stuck waiting for some child process or socket. For example, I would
like to implement a timeout parameter for psockcluster nodes,
equivalent to mccollect timeout. Below a poc that I hacked together,
which works on windows, but not linux/osx for above reasons.
eval_psock <- function(expr, envir=parent.frame(), timeout=60){
#create a child process
cluster <- parallel::makePSOCKcluster(1);
child <- cluster[[1]];
parallel:::sendCall(child, eval, list(quote(Sys.getpid())));
pid <- parallel:::recvResult(child);
#set the timeout
setTimeLimit(elapsed=timeout, transient=TRUE);
on.exit({
setTimeLimit(cpu=Inf, elapsed=Inf, transient=FALSE);
tools::pskill(pid); #win
tools::pskill(pid, tools::SIGKILL); #nix
parallel:::stopNode(child);
});
#send the actual call
parallel:::sendCall(child, eval, list(expr=substitute(expr),
envir=as.list(envir)));
myresult <- parallel:::recvResult(child);
#reset timelimit
setTimeLimit(cpu=Inf, elapsed=Inf, transient=TRUE);
#forks don't throw errors themselves
if(is(myresult,"try-error")){
#snow only returns the message, not an error object
stop(myresult, call.=FALSE);
}
#send the buffered response
return(myresult);
}
test <- function(){
n <- 1e8;
k <- 1e4;
#this should take more than 10 sec
eval_psock(svd(matrix(rnorm(n), k)), timeout=10);
}
system.time(test());
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