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From: "Bráulio Bhavamitra" <braulio@eita.org.br>
To: Eric Wong <e@80x24.org>
Cc: unicorn-public <unicorn-public@bogomips.org>
Subject: Re: Master hooks needed
Date: Fri, 3 Oct 2014 21:53:06 -0300	[thread overview]
Message-ID: <CAJri6_s61q4-yMTp8Ev8HizDBnjGXqusmkrJODYX64TtFd+8ZA@mail.gmail.com> (raw)
In-Reply-To: <20141003122222.GA11445@dcvr.yhbt.net>

The problem is actually worser, and the worker.nr == 0 can't be used.
I had to do something like this:

master_run = true

before_fork do |server, worker|
  if master_run
     #warm up server...

     #kill old pid...

     #disconnect active record

     master_run = false

  # other stuff for each worker

In the last example, using worker.nr == 0 would make the server crash
in case the worker 0 was killed/restarted.

Also the AR's disconnect and *many other stuff* people put on
before_fork should only be run once the master was preloaded, not for
every worker.

So I still think at least a hook like master_preloaded(server) is necessary.


On Fri, Oct 3, 2014 at 9:22 AM, 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.

  parent reply	other threads:[~2014-10-04  0:53 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
2014-10-03 17:50     ` Eric Wong
2014-10-03 18:12       ` Valentin Mihov
2014-10-04  0:53   ` Bráulio Bhavamitra [this message]
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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