Date: Tue, 11 Nov 2014 15:47:37 -0500 From: John Baldwin <jhb@freebsd.org> To: Charles Swiger <cswiger@mac.com> Cc: freebsd-current@freebsd.org, lev@freebsd.org, FreeBSD Current <current@freebsd.org> Subject: Re: Changing timezone without reboot/restarting each service? Message-ID: <201411111547.38001.jhb@freebsd.org> In-Reply-To: <5330A42B-CBCA-4349-BE12-777401272050@mac.com> References: <5460B143.6080206@FreeBSD.org> <201411111357.40061.jhb@freebsd.org> <5330A42B-CBCA-4349-BE12-777401272050@mac.com>
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On Tuesday, November 11, 2014 3:16:19 pm Charles Swiger wrote: > On Nov 11, 2014, at 10:57 AM, John Baldwin <jhb@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
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