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Andrew Stewart

2012-Apr-05 07:21 UTC

Problem restarting Unicorn

Hello,

I seem to be confused about how to restart Unicorn when deploying updates to a
Rails app via Capistrano.

I just had a problem where a bundled gem wasn''t being seen by the
Unicorn processes, even though app code I introduced at the same time was being
served by the Unicorn processes.  I had restarted Unicorn numerous times using
`bundle exec cap deploy:restart` (see the code below), which I thought was the
right way to do zero-downtime restarts, but my problem was only solved by doing
a hard restart of Unicorn with `bundle exec cap deploy:hard_restart`.

With each "normal" restart I tailed the stderr log to check everything
was ok; everything appeared fine, with gems refreshed etc.

Please could somebody explain what I''m doing wrong with my normal
restarts?

config/deploy.rb:

    set :unicorn_config, "#{current_path}/config/unicorn.rb"
    set :unicorn_pid,    "#{shared_path}/pids/unicorn.pid"

    namespace :deploy do
      task :start, :roles => :app, :except => { :no_release => true }
do
        run "cd #{current_path} && #{sudo_workaround} bundle exec
unicorn -c #{unicorn_config} -E #{rails_env} -D"
      end
      task :stop, :roles => :app, :except => { :no_release => true } do
        run "#{sudo_workaround} kill -s QUIT `cat #{unicorn_pid}`"
      end
      task :hard_stop, :roles => :app, :except => { :no_release => true
} do
        run "#{sudo_workaround} kill `cat #{unicorn_pid}`"
      end
      task :restart, :roles => :app, :except => { :no_release => true }
do
        run "#{sudo_workaround} kill -s USR2 `cat #{unicorn_pid}`"
      end
      task :hard_restart, :roles => :app, :except => { :no_release =>
true } do
        hard_stop
        start
      end
    end
    
    # Works around Ubuntu changing the PATH when you use sudo.
    # sudo''s path can find common commands like echo but not much else.
    def sudo_workaround
      "sudo env PATH=$PATH"
    end


config/unicorn.rb:

    APP_PATH = ''/var/www/apps/sparkle''
    worker_processes 4
    user ''rails'', ''rails''
    working_directory "#{APP_PATH}/current"
    listen "/tmp/unicorn_sparkle.sock", :backlog => 64
    timeout 30
    pid "#{APP_PATH}/shared/pids/unicorn.pid"
    stderr_path "#{APP_PATH}/shared/log/unicorn.stderr.log"
    stdout_path "#{APP_PATH}/shared/log/unicorn.stdout.log"
    preload_app true
    GC.respond_to?(:copy_on_write_friendly=) and GC.copy_on_write_friendly =
true
    
    before_fork do |server, worker|
      defined?(ActiveRecord::Base) and ActiveRecord::Base.connection.disconnect!
    
      old_pid = "#{server.config[:pid]}.oldbin"
      if old_pid != server.pid
        begin
          sig = (worker.nr + 1) >= server.worker_processes ? :QUIT : :TTOU
          Process.kill(sig, File.read(old_pid).to_i)
        rescue Errno::ENOENT, Errno::ESRCH
        end
      end
    end
    
    after_fork do |server, worker|
      defined?(ActiveRecord::Base) and ActiveRecord::Base.establish_connection
    end

This is all with Unicorn 4.2.0 and Rails 3.0.11.

Many thanks in advance,

Andy Stewart
----
http://airbladesoftware.com

Michael Guterl

2012-Apr-05 11:34 UTC

head link

Problem restarting Unicorn

On Thu, Apr 5, 2012 at 3:21 AM, Andrew Stewart
<boss at airbladesoftware.com> wrote:> Hello,
>
> I seem to be confused about how to restart Unicorn when deploying updates
to a Rails app via Capistrano.
>
> I just had a problem where a bundled gem wasn''t being seen by the
Unicorn processes, even though app code I introduced at the same time was being
served by the Unicorn processes. ?I had restarted Unicorn numerous times using
`bundle exec cap deploy:restart` (see the code below), which I thought was the
right way to do zero-downtime restarts, but my problem was only solved by doing
a hard restart of Unicorn with `bundle exec cap deploy:hard_restart`.
>
> With each "normal" restart I tailed the stderr log to check
everything was ok; everything appeared fine, with gems refreshed etc.
>
> Please could somebody explain what I''m doing wrong with my normal
restarts?
>
> config/deploy.rb:
>
> ? ?set :unicorn_config, "#{current_path}/config/unicorn.rb"
> ? ?set :unicorn_pid, ? ?"#{shared_path}/pids/unicorn.pid"
>
> ? ?namespace :deploy do
> ? ? ?task :start, :roles => :app, :except => { :no_release => true
} do
> ? ? ? ?run "cd #{current_path} && #{sudo_workaround} bundle
exec unicorn -c #{unicorn_config} -E #{rails_env} -D"
> ? ? ?end
> ? ? ?task :stop, :roles => :app, :except => { :no_release => true
} do
> ? ? ? ?run "#{sudo_workaround} kill -s QUIT `cat #{unicorn_pid}`"
> ? ? ?end
> ? ? ?task :hard_stop, :roles => :app, :except => { :no_release =>
true } do
> ? ? ? ?run "#{sudo_workaround} kill `cat #{unicorn_pid}`"
> ? ? ?end
> ? ? ?task :restart, :roles => :app, :except => { :no_release =>
true } do
> ? ? ? ?run "#{sudo_workaround} kill -s USR2 `cat #{unicorn_pid}`"
> ? ? ?end
> ? ? ?task :hard_restart, :roles => :app, :except => { :no_release
=> true } do
> ? ? ? ?hard_stop
> ? ? ? ?start
> ? ? ?end
> ? ?end
>
> ? ?# Works around Ubuntu changing the PATH when you use sudo.
> ? ?# sudo''s path can find common commands like echo but not much
else.
> ? ?def sudo_workaround
> ? ? ?"sudo env PATH=$PATH"
> ? ?end
>
>
> config/unicorn.rb:
>
> ? ?APP_PATH = ''/var/www/apps/sparkle''
> ? ?worker_processes 4
> ? ?user ''rails'', ''rails''
> ? ?working_directory "#{APP_PATH}/current"
> ? ?listen "/tmp/unicorn_sparkle.sock", :backlog => 64
> ? ?timeout 30
> ? ?pid "#{APP_PATH}/shared/pids/unicorn.pid"
> ? ?stderr_path "#{APP_PATH}/shared/log/unicorn.stderr.log"
> ? ?stdout_path "#{APP_PATH}/shared/log/unicorn.stdout.log"
> ? ?preload_app true
> ? ?GC.respond_to?(:copy_on_write_friendly=) and GC.copy_on_write_friendly =
true
>
> ? ?before_fork do |server, worker|
> ? ? ?defined?(ActiveRecord::Base) and
ActiveRecord::Base.connection.disconnect!
>
> ? ? ?old_pid = "#{server.config[:pid]}.oldbin"
> ? ? ?if old_pid != server.pid
> ? ? ? ?begin
> ? ? ? ? ?sig = (worker.nr + 1) >= server.worker_processes ? :QUIT :
:TTOU
> ? ? ? ? ?Process.kill(sig, File.read(old_pid).to_i)
> ? ? ? ?rescue Errno::ENOENT, Errno::ESRCH
> ? ? ? ?end
> ? ? ?end
> ? ?end
>
> ? ?after_fork do |server, worker|
> ? ? ?defined?(ActiveRecord::Base) and
ActiveRecord::Base.establish_connection
> ? ?end
>
> This is all with Unicorn 4.2.0 and Rails 3.0.11.
>
> Many thanks in advance,
>
You probably want to check out the Sandbox documentation here:
http://unicorn.bogomips.org/Sandbox.html

The section that I think is most relevant is related to setting the START_CTX:

Unicorn::HttpServer::START_CTX[0] = "/some/path/to/bin/unicorn"

Hope that helps.

Best,
Michael Guterl

Andrew Stewart

2012-Apr-10 08:52 UTC

head link

Problem restarting Unicorn

On 5 Apr 2012, at 13:34, Michael Guterl wrote:> On Thu, Apr 5, 2012 at 3:21 AM, Andrew Stewart <boss at
airbladesoftware.com> wrote:
>> I just had a problem where a bundled gem wasn''t being seen by
the Unicorn processes, even though app code I introduced at the same time was
being served by the Unicorn processes.  I had restarted Unicorn numerous times
using `bundle exec cap deploy:restart` (see the code below), which I thought was
the right way to do zero-downtime restarts, but my problem was only solved by
doing a hard restart of Unicorn with `bundle exec cap deploy:hard_restart`.
> 
> You probably want to check out the Sandbox documentation here:
> http://unicorn.bogomips.org/Sandbox.html
Thanks for the pointer to the Sandbox documentation, the one page on the Unicorn
website I hadn''t read.  The section on BUNDLE_GEMFILE for Capistrano
users was what I needed.

Yours,
Andy Stewart

mongrel unicorn - Apr 2012 - Problem restarting Unicorn

Problem restarting Unicorn

Problem restarting Unicorn

Problem restarting Unicorn