>> I don't understand what problem queued SIGCHLD was invented to >> address.
> My impression is that it allows you to get notified of state changes > of your child processes. If one signal could annonce several state > changes, how would you know what these state changes are? You'd call wait4(2) (or waitpid or wait3) with WNOHANG until it returned 0 (or returned -1 with ECHILD), collecting one child status change each time. You'd still need to do more or less the same with queued SIGCHLD; the only difference is it would let you skip the WNOHANG and call it exactly once per signal. (Unless a single child changed state twice, such as by being stopped and then killed, in which case the implementation had better queue wait stati as well or you'll be calling wait too often!) /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mo...@rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
