Rails 3 + Daemons gem: Exception when querying model

Question

As part of my rails project, we are going to use a daemon as a message queue listener to execute commands coming from a Rails RESTful webservice front end.

For ease of prototyping, we are using the Daemons gem to create a very simple daemon. Right now, it's super simple. Here is the code:

require 'rubygems'
require 'daemons'

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

Daemons.run_proc('aeon_server') do
    loop do
        empires = Empire.all
        sleep(5)
    end
end

Basically, it requires the things for daemons, then requires my Ruby environment, then launches in to the daemon. The daemon simply attempts to query everything from the Empires table. Then it sleeps and does it again.

When it goes to execute 'all', I get the following exception:

C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:109:in `write': closed stream (IOError)
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:109:in `block in flush'
from <internal:prelude>:10:in `synchronize'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:102:in `flush'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:126:in `auto_flush'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:67:in `add'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:78:in `debug'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract_adapter.rb:206:in `rescue in log'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract_adapter.rb:199:in `log'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/sqlite_adapter.rb:135:in `execute'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/sqlite_adapter.rb:284:in `select'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/query_cache.rb:56:in `select_all'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/base.rb:468:in `find_by_sql'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/relation.rb:64:in `to_a'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/relation/finder_methods.rb:143:in `all'
from C:in `all'
from script/aeon_server_control.rb:9:in `block (2 levels) in <main>'
from script/aeon_server_control.rb:7:in `loop'
from script/aeon_server_control.rb:7:in `block in <main>'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:249:in `call'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:249:in `block in start_proc'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:260:in `call'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:260:in `start_proc'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:293:in `start'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/controller.rb:73:in `run'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons.rb:195:in `block in run_proc'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/cmdline.rb:109:in `call'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/cmdline.rb:109:in `catch_exceptions'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons.rb:194:in `run_proc'
from script/aeon_server_control.rb:6:in `<main>'

Any idea why ActiveSupport is throwing this exception? Are there additional steps I need to "bootstrap" my rails environment in to the daemon, beyond just requiring the environment?

Answer 1

There're some intricacies with regard to file descriptors when the process is forked/spawned/whatever-it-is-called-on-windows.

Try to reinstantiate a logger after you do Daemons.run_proc('aeon_server') with Rails.logger = ActiveSupport::BufferedLogger.new('/path/to/log')