[Zope3-dev] Is there an alternative to zdaemon?

[Jim Fulton]

Sascha Ottolski wrote:
> Am Freitag, 22. Dezember 2006 21:55 schrieb Jim Fulton:
> Does anyone know of something
>> that does what zdaemon does?  daemontools seems somewhat close:
>>
>>    http://cr.yp.to/daemontools.html
>>
>> Going from the documentation, it doesn't seem to be as clever about
>> application restart.  The documentation says nothing about
>> distinguishing between normal and abnormal restarts or avoiding
>> useless restarts when there are start-up errors.
> 
> daeomontools are definetely worth looking, i use it for some years now, 
> and never had problems. it wasn't updated in almost five years, since 
> it just works.
> 
> you are right about the restart issue: if a supervised process dies, 
> it's restarted, no matter why it died. what would an abnormal restart 
> be, that should not take place, anyway? 

An abnormal exit is an exit due to some error, such as a segmentation
fault or running out of memory.

 > in the sense, how would the
> supervisor know thats it's abnormal?

It can check the exit status.  Normal shutdowns typycally exit with
status 0.  zdaemon (and supervisor2, which was obviously inspired by
zdaemon) has an exit-codes option to configure which exit codes
are normal.  If the supervisor exists with one of these exit codes,
it should not be restarted.

> FWIW, there's also "runit", obviously developed in the same spirit but 
> independend of daemontools: http://smarden.org/runit/useinit.html

This wants to run as process 1.  This seems a bit intrusive.

> And the python coded Supervisor2 made by Chris McDonough 
> http://www.plope.com/software/supervisor2/

This is interesting.

Jim

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