svn commit: r241576 - in head/usr.sbin/cron: cron crontab lib

[Ian Lepore]

On Mon, 2012-10-15 at 22:26 +0200, Pawel Jakub Dawidek wrote:
> On Mon, Oct 15, 2012 at 08:21:50AM +0000, Maxim Sobolev wrote:
> > Author: sobomax
> > Date: Mon Oct 15 08:21:49 2012
> > New Revision: 241576
> > URL: http://svn.freebsd.org/changeset/base/241576
> > 
> > Log:
> >   Add per-second scheduling into the cron(8). Right now it's
> >   only available via the new @every_second shortcut. ENOTIME to
> >   implement crontab(5) format extensions to allow more flexible
> >   scheduling.
> >   
> >   In order to address some concerns expressed by Terry Lambert
> >   while discussing the topic few years ago, about per-second cron
> >   possibly causing some bad effects on /etc/crontab by stat()ing
> >   it every second instead of every minute now (i.e. atime update),
> >   only check that database needs to be reloaded on every 60-th
> >   loop run. This should be close enough to the current behaviour.
> >   
> >   Add "@every_minute" shortcut while I am here.
> 
> Do I read the code correctly and the cron deamon will wake up every
> second now even if @every_second is not used at all?

It appears to, which I don't think is a bad thing at all.  But the way
it waits is to wake up, do some work, and go back to sleep for an
integer 1 second.  That will occasionally lead to a second in which no
wakeup happens, as the "do some work" part always takes some fraction of
a second.

-- Ian