Date: Sun, 7 Jan 2001 18:36:29 -0500 From: Bill Vermillion <bill@bilver.wjv.com> To: hackers@FreeBSD.ORG Subject: Re: freebsd-hackers-digest V5 #1 Message-ID: <20010107183629.A4125@wjv.com> In-Reply-To: <bulk.28066.20010107124732@hub.freebsd.org>; from owner-freebsd-hackers-digest@FreeBSD.ORG on Sun, Jan 07, 2001 at 12:47:32PM -0800 References: <bulk.28066.20010107124732@hub.freebsd.org>
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> Date: Sun, 7 Jan 2001 05:07:06 -0800 (PST) > From: Gordon Tetlow <gordont@bluemtn.net> > Subject: Re: OT: silence as an answer? (was: how to test out cron.c changes?) > Hello there! > On Fri, 5 Jan 2001, Doug Barton wrote: > > Gerhard Sittig wrote: > [snip] > > Consider the following. We are in the spring and DST is > > "springing forward" at 2am. We have a job scheduled at 2:15 > > that takes one hour to run. There is another job scheduled at > > 3:20 that ABSOLUTELY POSITIVELY cannot run unless the first > > job finishes. Aside from the fact that this is bad design, how > > should cron handle this situation? .... > I think this is a really horrible example. It is impossible for > FreeBSD to expect to catch bad design on a local administrator's > part. The admin should implement some sort of semaphore (a file in > /tmp) or just append the dependent job to the first job. We can't > insulate stupidity, at least we shouldn't, otherwise FreeBSD is > going to start looking more like Windows. I agree on that. Cron can't know the just how a program runs. Taking the above example and shifting the first program back to prior to 2AM - and that it take over an hour to run - what happens when a the clock springs forward and the hour is missing. The job wasn't scheduled in the 2AM black hole area. Programmers do have to consider DST. That's what we get paid for, right. Just like getting things like Y2K straight :-0 And the last Y2K bugs occured this past week. In Norway [as I recall] on train schedules, because 12/31/2000 hadn't been tested and this week in the US when all the 7/11 stores POS system though 01/01/01 was 1901, and that all the credit cards were invalid. > I think that cron is broken because it doesn't handle DST shift > properly. Just my opinion though, and we seem to get plenty of > those around here =) ISTR that at least in the last couple of years some of the OSes handle the DST shift properly. eg - not running a job twice for example. I've not had a problem on BSD - but then I don't have anything scheduled in those hours except things that run every hour. -- Bill Vermillion - bv @ wjv . com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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