Re: multiple job instances with cron (was: New virtual package: cron-daemon)
* Bernd Eckenfels <lists@lina.inka.de> [040606 15:34]:
> In respect to that, does anybody know, why the default behaviour of crons is
> to start multiple instances of the same job, if the execution times overlap.
> Is this intentional or only because it makes book keeping simpler? I know
> cron jobs should protect themself against multiple invocations, but IMHO it
> would increase useability and stability greatly, if cron does not schedule a
> job after the other is not finished.
I guess every decision in this is somehow wrong. One wants normally long
running cron-jobs not be harmed by revocation, but one normaly also
wants a way that blocked cron-job instanced will not block further
occourance.
I believe exim had (don't know if still has) the situation that the
cronjob to processed queued things would stop the old instance and try
the work itself. This way some error causing the old instance to hang
will not block it forever. It only becomes probelmatic when the time
to parse the queue before sending out the first message became longer
then the time between two cronjobs...
Hochachtungsvoll,
Bernhard R. Link
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