Re: `s6-svc -o -wD` doesn't wait for service to go down

From: Laurent Bercot <>
Date: Fri, 20 May 2016 17:22:59 +0200

On 20/05/2016 16:11, Max Ivanov wrote:
> That is what I ended up doing, but without an `-wu` part, thanks for the tip.

  Yes, the -wu is necessary to avoid a race condition where s6-svwait could
run before the service is actually up, and would exit right away (the same
issue you encountered initially).

> What concerned me at first is that s6-svwait page explicitly states
> that "s6-svwait only waits for notifications; it never polls.", which
> might mean that if service went down before s6-svwait started, then it
> can't wait forever for "down" notification. I then checked with two
> consecutive `s6-svwait -D` calls and both detected that service
> already down and exited, so s6-svwait is actually level-triggered, not
> edge triggered.

  Yes, s6-svwait never polls... after the first time. It still has to check
the initial state of the service once at start, like all the tools in the
family. So if the initial state is down, s6-svwait -D will immediately

Received on Fri May 20 2016 - 15:22:59 UTC

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