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From: Valentin Mihov <valentin.mihov@gmail.com>
To: Eric Wong <e@80x24.org>
Cc: "Bráulio Bhavamitra" <braulio@eita.org.br>,
	unicorn-public <unicorn-public@bogomips.org>
Subject: Re: Master hooks needed
Date: Fri, 3 Oct 2014 15:36:28 +0300	[thread overview]
Message-ID: <CAC=mCcmx1yTiU0XRP+gDJ7qHECEK9GT7ZOK57bbDG3K-OX6H4Q@mail.gmail.com> (raw)
In-Reply-To: <20141003122222.GA11445@dcvr.yhbt.net>

On Fri, Oct 3, 2014 at 3:22 PM, Eric Wong <e@80x24.org> wrote:
>
> Bráulio Bhavamitra <braulio@eita.org.br> wrote:
> > Hello all,
> >
> > If I need to hook something after master load, I'm currently doing:
> >
> > before_fork do |server, worker|
> >   # worker 0 is the first to init, so hold the master here
> >   if worker.nr == 0
> >      #warm up server...
> >
> >      #kill old pid...
> >   end
> >
> >   # other stuff for each worker
> > end
> >
> > Both operations I currently do (server warm up and old pid kill) need
> > to be run only once, and not for every worker as before_fork does,
> > that's why I had to put the condition seen above.
>
> The above is fine if your first worker never dies.  I think you can add
> a local variable to ensure it only runs the first time worker.nr == 0 is
> started, in case a worker dies.  Something like:
>
>     first = true
>     before_fork do |server, worker|
>       # worker 0 is the first to init, so hold the master here
>       if worker.nr == 0 && first
>          first = false
>          #warm up server...
>
>          #kill old pid...
>       end
>
>       # other stuff for each worker
>     end
>
> For what it's worth, I'm not a fan of auto-killing the old PID in the
> unicorn config and regret having it in the example config.  It's only
> for the most memory-constrained configs and fragile (because anything
> with pid files is always fragile).
>
> > So hooks for master is needed, something like
> > master_after_load(server) and master_init(server).
> >
> > What do you think?
>
> rack.git also has a Rack::Builder#warmup method.  Aman originally
> proposed it for unicorn, but it's useful outside of unicorn so
> we moved it to Rack.
>
> In general, I'm against adding new hooks/options because they tend to
> make maintainability and documentation harder for ops folks.
> I still have nightmares of some Capistrano config filled with hooks
> from years ago :x
>
> Features like these also makes migrating away from unicorn harder, so
> that is another reason we ended up adding #warmup to Rack and not
> unicorn.
>

Isn't it much better to do the warmup in an initializer instead in
unicorn? This way you can preload_app=true and the master will execute
the warmup code and fork. Killing the old pid is probably stopping you
from do that, right?

--Valentin

  reply	other threads:[~2014-10-03 12:36 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-03 11:34 Master hooks needed Bráulio Bhavamitra
2014-10-03 12:22 ` Eric Wong
2014-10-03 12:36   ` Valentin Mihov [this message]
2014-10-03 17:50     ` Eric Wong
2014-10-03 18:12       ` Valentin Mihov
2014-10-04  0:53   ` Bráulio Bhavamitra
2014-10-04  1:22     ` Eric Wong
2014-10-04  1:35       ` Bráulio Bhavamitra
2014-10-04  1:57         ` Eric Wong
2014-10-04  2:04           ` Bráulio Bhavamitra
2014-10-04  2:25             ` Eric Wong

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