Re: do packages depend on lexical order or {daily,weekly,monthly} cron jobs?
On Sat, 27 Jul 2019 19:02:16 +0100, Ian Jackson
<ijackson@chiark.greenend.org.uk> wrote:
>Marc Haber writes ("do packages depend on lexical order or {daily,weekly,monthly} cron jobs?"):
>> Do you people know about packages that have cron jobs that depend on
>> execution order? Would it probably be a good idea to proactively put
>> language into the Policy Manual Chapter 9.5 that scripts put into the
>> /etc/cron.{daily,weekly,monthly} MUST NOT depend on any execution
>> order and MUST be prepared to run in parallel?
>
>"Does not depend on order" and "can be run in parallel" are not the
>same.
Right. I didn't mean to imply that.
>I worry about additional concurrency. Unlike ordering bugs,
>concurrency bugs are hard to find by testing. So running these
>scripts in parallel is risky.
>
>And, I think running cron.fooly scripts in parallel is a bad idea.
>The objective is to run them "at some point", not to get it done as
>soon as possible. Running them in sequence will save electricity,
>may save wear on components, and will reduce overall impact on other
>uses of the same system.
I fully agree with that. However, moving away from "in sequence" thing
would greatly ease the migration to systemd timers, making it easier
to get away without crond on many systems.
I am wondering whether this is something we should think about giving
up in future. We have given up so many things since we moved to
systemd, would it be worth throwing this out of the window as well?
Setting RandomizeDelaySecs sufficiently high on our daily jobs would
probably help to chop off the load pike that especially virtualization
setups running many Debian instances suffer from at 06:25 or 07:35. I
think this could be a net gain worth pursuing.
Grüße
Marc
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Marc Haber | " Questions are the | Mailadresse im Header
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