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On 12/1/06, ara.t.howard / noaa.gov <ara.t.howard / noaa.gov> wrote:
>
> On Sat, 2 Dec 2006, Tim Pease wrote:
>
> >> rather, i think one must
> >>
> >>    1) constrain even runner to check only every n seconds, ala cron
> >>
> >
> > You're still going to have the missed events problem with the runner
> > regardless of the time granularity. If you only check every ten seconds
> but
> > notifications take twenty, then a whole set of notifications are missed.
>
> nah.  you'd raise an error if events were scheduled at finer than 'n'.  in
> cron it's simply not possible - same thing.  alternatively you can merge
> into
> minute buckets.
>
> > Sounds like (regardless of using cron style runner or Runt "next time"
> > conventions) missed notifications need to be handled in a predictable
> > manner.
>
> > 1) just drop them
> > 2) send out an extra notification immediately
> > 3) queue up the missed notifications for the next time
>
> agreed.  i'd add:
>
>    4) call user handler - specification possible at event creation
>
> there is some uber cron thingy on macs that handles this i think...
> anyone?


I believe you're referring to launchd.
http://developer.apple.com/macosx/launchd.html *The correct title of this
article is launchd. The initial letter is shown capitalized due to technical
restrictions<http://en.wikipedia.org/wiki/Wikipedia:Naming_conventions_%28technical_restrictions%29#Lower_case_first_letter>
.*

*"launchd* is a unified, open
source<http://en.wikipedia.org/wiki/Open_source> service
management<http://en.wikipedia.org/wiki/Operating_System_service_management>
framework <http://en.wikipedia.org/wiki/Framework> for starting, stopping
and managing daemons<http://en.wikipedia.org/wiki/Daemon_%28computer_software%29>,
programs <http://en.wikipedia.org/wiki/Computer_program> and
scripts<http://en.wikipedia.org/wiki/Shell_script>.
It was introduced with Mac OS X
v10.4<http://en.wikipedia.org/wiki/Mac_OS_X_v10.4>
/Darwin <http://en.wikipedia.org/wiki/Darwin_%28operating_system%29> v8.0,
and is licensed under the Apache
License<http://en.wikipedia.org/wiki/Apache_License>.
Dave Zarzycki <http://en.wikipedia.org/wiki/Dave_Zarzycki> is credited with
designing and maintaining launchd.

The launchd daemon<http://en.wikipedia.org/wiki/Daemon_%28computer_software%29>is
essentially a replacement for
init <http://en.wikipedia.org/wiki/Init>,
rc<http://en.wikipedia.org/wiki/Unix_security>,
the init.d <http://en.wikipedia.org/w/index.php?titleit.d&actionùÊt>and
rc.d <http://en.wikipedia.org/w/index.php?title
.d&actionùÊt> scripts,
SystemStarter <http://en.wikipedia.org/wiki/SystemStarter> (Mac OS X),
inetd<http://en.wikipedia.org/wiki/Inetd>and
xinetd <http://en.wikipedia.org/wiki/Xinetd>,
atd<http://en.wikipedia.org/w/index.php?title&actionùÊt>,
crond <http://en.wikipedia.org/wiki/Crond> and
watchdogd<http://en.wikipedia.org/w/index.php?title
tchdogd&actionùÊt>.
Apple has stated that it intends to eliminate all of the aformentioned
services in favor of launchd. As of OS X v10.4 Apple has moved most of the
processes handled by the previously mentioned daemons to launchd. By
consolidating all the launch services into one program, launchd
significantly shortens boot time on slow computers."[1]
[1] http://en.wikipedia.org/wiki/Launchd

>>    2) have the event interalize the time iteration itself so it can start
> >>    threads whenever it needs
> >>
> >
> > Will this cause a slow thread death with lots and lots of events?  The
> > ruby thread scheduler might eat up all your processor trying to
> > schedule 1000+ threads?
>
> it sure could.  i'm of the opinion though, that users should be allowed to
> shoot themselves in the foot - if you want to schedule 40,000 events per
> second then fine, maybe your quantum computer can actually handle it!  ;-)
>
> a warning or hard/soft limits might be a good compromise.
>
> > At the last ruby group meeting, Nathan Witmer showed me a nice little
> > "thread per notification" system he put together. It sounds very useful
> for
> > this project of yours.
>
> link?
>
> -a
> --
> if you want others to be happy, practice compassion.
> if you want to be happy, practice compassion.  -- the dalai lama
>
>

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