Re: Shepherd does not recycle zombie processes

[Carlo Zancanaro <carlo@zancanaro.id.au>]

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Hey Ludo!

On Mon, Nov 07 2016, Ludovic Courtès wrote
> Could it be that you invoke the ‘daemonize’ action after 
> respawnable processes have been started?  The manual has this 
> caveat (info "(shepherd) The root and unknown services"):
>
>   ‘daemonize’ 
>        Fork and go into the background.  This should be called 
>        before respawnable services are started, as otherwise we 
>        would not get the ‘SIGCHLD’ signals when they terminate.

Yeah, I saw that note in the documentation. I used to have

    (action 'shepherd 'daemonize)

as the first line in ~/.config/shepherd/init.scm. Is there some 
other way that I was supposed to do that?

With that line in place, Shepherd will leave behind a process 
every time I stop/start a service.

I have attached an example init.scm that does this for me. If I 
start: 

    shepherd -c init.scm

and then run:

    herd stop sleep
    herd start sleep
    herd stop sleep
    herd start sleep
    herd stop sleep

then I will have three zombie sleep processes underneath my 
Shepherd process. (If the service were respawnable then it also 
would fail to restart the service.)

I assume this behaviour is wrong, but if I'm doing something wrong 
then please let me know what it is.

Carlo


[-- Attachment #1.2: init.scm --]
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(action 'shepherd 'daemonize)

(define sleep
  (make <service>
    #:provides '(sleep)
    #:start (make-forkexec-constructor '("sleep" "100"))
    #:stop (make-kill-destructor)))

(register-services sleep)
(start sleep)

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