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Rails 3.1 + Daemons gem won't let me access my database

I am trying to configure a daemon for my Rails 3.1 application running on a Unbuntu server. Just something simple:

require File.expand_path('../../config/environment',  __FILE__)
require 'rubygems'
require 'daemons'

Daemons.run_proc('my_script') do
  loop do
    puts BlogPost.count
    sleep(5)
  end
end

But when I get to BlogPost.count, I get the following error:

/usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `query': Mysql2::Error: MySQL server has gone away: SHOW FIELDS FROM `blog_posts` (ActiveRecord::StatementInvalid)
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `execute'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:244:in `log'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.1.0/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:239:in `log'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `execute'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:473:in `columns'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:95:in `initialize'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:185:in `with_connection'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:92:in `initialize'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `call'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `default'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `[]'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `columns'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:722:in `column_names'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:192:in `aggregate_column'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:213:in `execute_simple_calculation'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:187:in `perform_calculation'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:155:in `calculate'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:58:in `count'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:445:in `__send__'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:445:in `count'
from script/background_job_processor_control.rb:22

Any idea why my script cannot connect to MySQL? If I put the code BlogPost.countbefore Daemons.run_proc, I can just connect to MySQL.

---------- EDIT: SOLVING! ------------

For anyone interested in a solution, I had to do three things to get this to work:

  • Enable bundle execwhen you start / stop my demon: RAILS_ENV=production bundle exec myscript.rb start.
  • At this point, I stopped getting the MySQL2 error, but started getting a log error. The solution was to add the following code to the block run_proc:ActiveRecord::Base.logger = ActiveSupport::BufferedLogger.new('/path/to/log/file.log')
  • , Rails run_proc script.

script :

require 'rubygems'
require 'daemons'

Daemons.run_proc('my_script') do 
  require File.expand_path('../../config/environment',  __FILE__)
  ActiveRecord::Base.logger = ActiveSupport::BufferedLogger.new('/path/to/log/file.log')
  loop do
    puts BlogPost.count
    sleep(5)
  end
end
+5
2

Rails () script, :

bundle exec my_script_ctl start
+1

, , , script, :

# app env
ENV['RAILS_ENV'] = 'production'
require File.expand_path(File.dirname(__FILE__) + "/../config/environment")

# disconnect first
ActiveRecord::Base.connection.disconnect!

# Become a daemon
Daemons.daemonize

# connect again
ActiveRecord::Base.establish_connection ENV['RAILS_ENV']

# ... do what you need

, .

+1

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