Re: Changing timezone without reboot/restarting each service?

On Tuesday, November 11, 2014 3:16:19 pm Charles Swiger wrote:
> On Nov 11, 2014, at 10:57 AM, John Baldwin <jhb_at_freebsd.org> wrote:
> > On Monday, November 10, 2014 7:36:19 am Lev Serebryakov wrote:
> >> 
> >> After changing timezones in Russia (with replacing /etc/localtime
> >> with new file), I found that cron works in "old" timezone till
> >> restart. And all other services do the same, but cron is most obvious
> >> here :)
> >> 
> >> Looks like libc reads timezone only once and it could not be chamged
> >> for process without restart (which leads to, effectivly, restart of
> >> whole server).
> >> 
> >> Is it known problem? I think, it should be fixed somehow. I
> >> understand, that re-check timezone file on each time-related call
> >> could be expensive, though :(
> > 
> > In practice, timezone changes are very rare, so rechecking the file is
> > quite expensive to do.  I think having to restart processes is fine for this.
> 
> In theory, timezone changes should be very rare.
> 
> We've actually had about ten TZ updates in 2014; the most recent was FET -> MSK
> for Belarus plus minor tweaks to IDT vs ICT.  If you're working within the scope
> of a single country, I suspect that one could ignore the bulk of TZ updates and
> be fine most of the time.
> 
> If you're world-wide, however, TZ update frequency becomes more noticeable....

The vast majority of updates are historical changes however.  Having used a
timezone-aware version of cron for an international company so we can schedule
jobs across multiple timezones for a single machine (times N machines scattered
around the globe) for the last 4 or 5 years, FET -> MSK was the first time we
had a timezone change in that span that actually impacted our operations (and
we've just restarted cron / rebooted to cope).

-- 
John Baldwin