Date: Wed, 3 Aug 2022 07:12:11 -0700 From: Cy Schubert <Cy.Schubert@cschubert.com> To: Xin Li <delphij@delphij.net> Cc: d@delphij.net, Warner Losh <imp@bsdimp.com>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: cron @shutdown Message-ID: <20220803071211.78164688@slippy> In-Reply-To: <e9900e0f-c563-24ff-53f8-775c332297cf@delphij.net> References: <20220802145433.E2DB351D@slippy.cwsent.com> <CANCZdfo9JZzH8GkA%2Bd1ddi6cATfbN1e0%2B5_j3ALDpmgT63EYDQ@mail.gmail.com> <20220802150243.242AF580@slippy.cwsent.com> <e9900e0f-c563-24ff-53f8-775c332297cf@delphij.net>
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On Tue, 2 Aug 2022 22:37:36 -0700 Xin Li <delphij@delphij.net> wrote: > On 8/2/22 08:02, Cy Schubert wrote: > > In message <CANCZdfo9JZzH8GkA+d1ddi6cATfbN1e0+5_j3ALDpmgT63EYDQ@mail.gmail.c > > om> > > , Warner Losh writes: > >> --000000000000543e5405e5435396 > >> Content-Type: text/plain; charset="UTF-8" > >> > >> On Tue, Aug 2, 2022, 8:54 AM Cy Schubert <Cy.Schubert@cschubert.com> wrote: > >> > >>> Hi, > >>> > >>> Does anyone think there might be some utility with an @shutdown crontab(5) > >>> "nickname" similar to @reboot but instead when cron shuts down? > >>> > >>> I pointed out to one of my customers that @reboot might be an option > >>> instead of an rc script (or in his case a systemd unit file). Not that an > >>> @reboot for FreeBSD cron would contribute to solving his Linux problem but > >>> might our users be interested in something like this? > >>> > >> > >> > >> If it's simple and increases portability, I'm all for it. > > > > It's simple but there's no Linux equivalent, yet. My thoughts are to > > implement in FreeBSD then canvas then submit a pull request to the Linux > > Vixie Cron maintainer and discuss with the various Linux vendors. > > I think it would be worth updating our cron with OpenBSD's cron(8) or a > newer vixie-cron version first. There are a lot of improvements that > would be useful for us too. We could look at OpenBSD's cron but the Vixie-cron, as installed on Red Hat, is IMO a regression as it doesn't implement some of the "nicknames" we already support. > > Regarding @shutdown, I'd second Warner that if it's simple to implement, > we should have it. However, we should also keep in mind that delaying > shutdown can be bad as eventually the shutdown process would send > SIGKILL to everyone, and the timer starts before cron receives SIGTERM. > So the user *might* want their software to be more robust with crashes > and developers should focus more on how to make the software to recover > quickly from a crash, because crash can not be avoided: hardware issue, > user sending SIGKILL, bugs, etc. can all cause it to crash. On the other > hand, making too much effort with how to "properly" shutdown generally > makes the situation worse, and sometimes they don't contribute to a > better stop-to-start-and-ready-to-use time compared to a > crash-only-with-fast-recovery design, so while it can be really useful > for some scenarios, it's probably not the best thing that the user > should do. This makes my suggestion regressive as there is a greater chance an end-user script would exceed the ninety second timeout. -- Cheers, Cy Schubert <Cy.Schubert@cschubert.com> FreeBSD UNIX: <cy@FreeBSD.org> Web: http://www.FreeBSD.org NTP: <cy@nwtime.org> Web: https://nwtime.org e**(i*pi)+1=0
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