Eventmachine talk - Aug 2006 - EM and daemonize from raa

Any reason why the following code wouldn''t work with EM?  I included
the Daemonize module at the end to show what it does, it''s fairly
short.  When I run this EM won''t accept connections.  With daemonize()
commented out it works fine.  Must be something about how it forks
that EM doesn''t like.

class MyServer
  include Daemonize

  def initialize
    daemonize()
      EventMachine::run {
        EventMachine::start_server "127.0.0.1", 8081, Netstring
      }
  end
end
server = MyServer.new

----------------------------------------------------------------------------------------
module Daemonize
  VERSION = "0.1.2"
  # maximum process limit for the system has been reached
  def safefork
    tryagain = true

    while tryagain
        if pid = fork
          return pid
        end
      rescue Errno::EWOULDBLOCK
      end
    end
  end

  # This method causes the current running process to become a daemon
  # If closefd is true, all existing file descriptors are closed
  def daemonize(oldmode=0, closefd=false)
    srand # Split rand streams between spawning and daemonized process
    safefork and exit # Fork and exit from the parent

    # Detach from the controlling terminal
    unless sess_id = Process.setsid
      raise ''Cannot detach from controlled terminal''
    end

    # Prevent the possibility of acquiring a controlling terminal
    if oldmode.zero?
      trap ''SIGHUP'', ''IGNORE''
      exit if pid = safefork
    end

    Dir.chdir "/"   # Release old working directory
    File.umask 0000 # Insure sensible umask

    if closefd
      # Make sure all file descriptors are closed
      ObjectSpace.each_object(IO) do |io|
        unless [STDIN, STDOUT, STDERR].include?(io)
          io.close rescue nil
        end
      end
    end

    STDIN.reopen "/dev/null"       # Free file descriptors and
    STDOUT.reopen "/dev/null", "a" # point them somewhere
sensible
    STDERR.reopen STDOUT           # STDOUT/STDERR should go to a logfile
    return oldmode ? sess_id : 0   # Return value is mostly irrelevant
  end
end

Snacktime, as you observed to me via IM, the problem appears to be related
to database connections disappearing across the daemonize fork. I was able
to run EventMachine in a daemonized process on Linux with no problem. Please
let us know here when you solve it. Thanks.

On 8/22/06, snacktime <snacktime at gmail.com>
wrote:
>
> Any reason why the following code wouldn''t work with EM?  I
included
> the Daemonize module at the end to show what it does, it''s fairly
> short.  When I run this EM won''t accept connections.  With
daemonize()
> commented out it works fine.  Must be something about how it forks
> that EM doesn''t like.
>
> class MyServer
>   include Daemonize
>
>   def initialize
>     daemonize()
>       EventMachine::run {
>         EventMachine::start_server "127.0.0.1", 8081, Netstring
>       }
>   end
> end
> server = MyServer.new
>
>
>
----------------------------------------------------------------------------------------
> module Daemonize
>   VERSION = "0.1.2"
>   # maximum process limit for the system has been reached
>   def safefork
>     tryagain = true
>
>     while tryagain
>         if pid = fork
>           return pid
>         end
>       rescue Errno::EWOULDBLOCK
>       end
>     end
>   end
>
>   # This method causes the current running process to become a daemon
>   # If closefd is true, all existing file descriptors are closed
>   def daemonize(oldmode=0, closefd=false)
>     srand # Split rand streams between spawning and daemonized process
>     safefork and exit # Fork and exit from the parent
>
>     # Detach from the controlling terminal
>     unless sess_id = Process.setsid
>       raise ''Cannot detach from controlled terminal''
>     end
>
>     # Prevent the possibility of acquiring a controlling terminal
>     if oldmode.zero?
>       trap ''SIGHUP'', ''IGNORE''
>       exit if pid = safefork
>     end
>
>     Dir.chdir "/"   # Release old working directory
>     File.umask 0000 # Insure sensible umask
>
>     if closefd
>       # Make sure all file descriptors are closed
>       ObjectSpace.each_object(IO) do |io|
>         unless [STDIN, STDOUT, STDERR].include?(io)
>           io.close rescue nil
>         end
>       end
>     end
>
>     STDIN.reopen "/dev/null"       # Free file descriptors and
>     STDOUT.reopen "/dev/null", "a" # point them
somewhere sensible
>     STDERR.reopen STDOUT           # STDOUT/STDERR should go to a logfile
>     return oldmode ? sess_id : 0   # Return value is mostly irrelevant
>   end
> end
> _______________________________________________
> Eventmachine-talk mailing list
> Eventmachine-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/eventmachine-talk
>
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Once I moved the database connection startup to after the fork
everything works fine.