Messages in this thread | | | Date | Sun, 11 May 2003 23:26:06 -0400 | From | Chris Friesen <> | Subject | Re: [RFC] new syscall to allow notification when arbitrary pids die |
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Muli Ben-Yehuda wrote: > On Sat, May 10, 2003 at 02:29:54AM -0400, Chris Friesen wrote: > > >>I see two immediate uses for this. One would be to enable a "watcher" >>process which can do useful things on the death of processes which >>registered with it (logging, respawning, notifying other processes, >>etc). >> > > Do it from user space, kill(pid, 0), check for ESRCH. I might see the > benefit of a new system call if it was synchronous (wait() semantics), > but since signal delivery is asynch anyway....
Exactly. I don't want to explicitly poll each process being monitored to see if it is still alive. That solution doesn't scale well--what happens when you are monitoring 5000 processes and you want to make sure that you catch them within a certain amount of time? You end up spending a lot of cpu time doing the monitoring.
> There's already a well established way to do what you want (get > non-immediate notification of process death). What benefit would your > approach give?
Its cheaper and faster. It only costs a single call for each process, and then you get notified immediately when it dies.
Chris
-- Chris Friesen | MailStop: 043/33/F10 Nortel Networks | work: (613) 765-0557 3500 Carling Avenue | fax: (613) 765-2986 Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com
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