frollapply: wait for terminated parallel processes

While handling an interrupt, ask mccollect() to wait for the child
process to exit (with a warning) in order to avoid producing zombies.
Otherwise a process that is too slow to react to SIGTERM will remain a
zombie until the parent process exits.

Author: aitap

R/frollapply.R

@@ -412,7 +412,7 @@ frollapply = function(X, N, FUN, ..., by.column=TRUE, fill=NA, align=c("right","
               # nocov start
               suspendInterrupts({
                 lapply(jobs, function(pid) try(tools::pskill(pid), silent = TRUE))
-                parallel::mccollect(jobs, wait = FALSE)
+                parallel::mccollect(jobs)
               })
               # nocov end
               # Let the interrupt continue without invoking restarts