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From: Eric Wong <e@80x24.org>
To: Christos Trochalakis <yatiohi@ideopolis.gr>
Cc: Dmitry Smirnov <onlyjob@debian.org>,
	Hleb Valoshka <375gnu@gmail.com>,
	unicorn@packages.debian.org, unicorn-public@bogomips.org
Subject: Re: [DRE-maint] unicorn: native systemd service
Date: Sat, 27 Jun 2015 03:05:01 +0000	[thread overview]
Message-ID: <20150627030501.GA24759@dcvr.yhbt.net> (raw)
In-Reply-To: <20150626114129.GA25883@luke.ws.skroutz.gr>

Christos Trochalakis <yatiohi@ideopolis.gr> wrote:
> On Thu, Jun 25, 2015 at 11:26:26PM +0000, Eric Wong wrote:
> >With socket activation, you should just be able to kill unicorn using
> >SIGQUIT (just master, or even all workers) and restart without ever
> >dropping a connection.  I do NOT suggest using SIGTERM for unicorn,
> >since that'll cause the master to kill all workers ASAP.
> Yes, you are right socket activation is also an option! I have made some
> experiments with a simple rack app to test it.
> systemd uses the LISTEN_FDS env variable that is an integer indicating the
> number of inherited file descriptors. Those FDs have consecutive numbers
> starting from `SD_LISTEN_FDS_START` which is `3` (man sd_listen_fds).
> So for example if LISTEN_FDS="2", UNICORN_FD should be "3,4". I used a
> simple wrapper script for that. Here is the full configuration:

OK, I'll probably add LISTEN_FDS and LISTEN_PID support to unicorn
directly so the wrapper is unnecessary.


> KillMode=mixed

I don't think KillMode=mixed is necessary, here.  systemd can send
SIGQUIT to workers.


> TCP socket options are not applied by unicorn on inherited sockets (TCPSocket
> === sock is false). systemd socket files have support for most options now but
> we might want unicorn to `setsockopt` them as well. For example,
> 'DeferAcceptSec', 'KeepAliveIntervalSec', 'NoDelay' are supported since v216, so
> they are not available in jessie (v215).

They are now :)


We don't have KeepAliveIntervalSec
(aka TCP_KEEPINTVL) since it's not-portable and probably over
Are you sure about that?

> socket activation is a really interesting setup, but personally I would not run
> it with a large application. Clients would have to wait for the new master to
> be up and running before a reply is returned, and that could take tenths of
> seconds. The USR2 rexec solves that problem since both old and new workers are
> accepting on the socket and we can kill the old ones when we are ready. In that
> case the PIDFile trick is handy to support zero downtime restarts with no
> latency.

Is it possible to make systemd fire up two unicorn masters?
That would be a nice feature to have with socket activation.

  reply	other threads:[~2015-06-27  3:05 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <16714105.fRFKlev1fp@debstor>
     [not found] ` <3137844.nsIDTWmvl4@debstor>
     [not found]   ` <CAAB-Kc=s-uSK83PcfDsybPRiYvTaLVxcu2x4eWDPaTf27AJ_XQ@mail.gmail.com>
     [not found]     ` <1810167.FXDESjsu8Z@debstor>
2015-06-24 23:26       ` unicorn: native systemd service Eric Wong
2015-06-25 23:43         ` Dmitry Smirnov
2015-06-25 23:49           ` Eric Wong
     [not found]   ` <20150625083118.GA22140@luke.ws.skroutz.gr>
2015-06-25 23:26     ` [DRE-maint] " Eric Wong
2015-06-26 11:41       ` Christos Trochalakis
2015-06-27  3:05         ` Eric Wong [this message]
2015-06-27  4:01           ` [RFC] emulate sd_listen_fds for systemd support Eric Wong
2015-06-30  8:47             ` Christos Trochalakis
2015-07-05  0:27               ` [PATCH v2] " Eric Wong
2015-06-30  9:20           ` [DRE-maint] unicorn: native systemd service Christos Trochalakis
2015-06-30 17:30             ` Eric Wong
2015-07-08 13:08               ` Christos Trochalakis

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