From: "Serge E. Hallyn" <serge@hallyn.com>
To: Brett Neumeier <bneumeier@gmail.com>
Cc: Supervision <supervision@list.skarnet.org>
Subject: Re: Readiness notification exemplars
Date: Wed, 1 Apr 2020 09:21:22 -0500 [thread overview]
Message-ID: <20200401142122.GA30742@mail.hallyn.com> (raw)
In-Reply-To: <CAGSetNuLfBwTT_-F=HoDAoDYWoW1qHbfeVqD83BvSpJKpkwv=w@mail.gmail.com>
I've been considering for several years trying to push a kernel patch
which would provide a way for userspace to find out when someone starts
listening on some port. Based on problems I saw long ago in the late
days of upstart and early days of systemd, that seemed like it would
solve a not infrequent problem without having to make any changes to
the daemons. Upstart tried to solve it by making the daemons send a
sigstop when ready; systemd solves it by making the daemons support
socket notification; listen-notifiers could be entirely handled by
the dependency handler in the init system.
It's *still* on my list of todos. Maybe sufficient ridicule here will
help me knock it off the list :)
On Wed, Apr 01, 2020 at 08:23:26AM -0500, Brett Neumeier wrote:
> I read on http://skarnet.org/software/s6/notifywhenup.html:
>
> "...daemons can simply write a line to a file descriptor of their choice,
> then close that file descriptor, when they're ready to serve. This is a
> generic mechanism that some daemons already implement."
>
> I am curious, does anyone on this list know of examples of such daemons? I
> am considering creating and submitting patches for some daemon programs
> that I use that do *not* support this mechanism as yet, and am curious if
> it is as simple as it looks like it should be.
>
> Cheers!
>
> Brett
>
> --
> Brett Neumeier (bneumeier@gmail.com)
next prev parent reply other threads:[~2020-04-01 14:21 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-01 13:23 Brett Neumeier
2020-04-01 13:36 ` Casper Ti. Vector
2020-04-01 14:21 ` Serge E. Hallyn [this message]
2020-04-01 15:06 ` Laurent Bercot
2020-04-01 15:28 ` Serge E. Hallyn
2020-04-01 15:59 ` Laurent Bercot
2020-04-01 16:26 ` Serge E. Hallyn
2020-04-01 17:13 ` Laurent Bercot
2020-04-04 15:02 ` Serge E. Hallyn
2020-04-04 15:54 ` Laurent Bercot
2020-04-03 7:41 ` Jonathan de Boyne Pollard
2020-04-04 15:48 ` Serge E. Hallyn
2020-04-04 21:29 ` Laurent Bercot
2020-04-04 22:18 ` Serge E. Hallyn
2020-04-07 23:03 ` Brett Neumeier
2020-04-08 11:02 ` Laurent Bercot
2020-04-09 10:31 ` Jonathan de Boyne Pollard
2020-04-01 14:55 ` Laurent Bercot
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