Understanding Celluloid Concurrency

Question

Following are my Celluloid codes.

1. client1.rb One of the 2 clients. (I named it as client 1)

2. client2.rb 2nd of the 2 clients. (named as client 2

Answer 1

_{Managed to reproduce and fix the issue. Deleting my previous answer. Apparently, the problem lies in sleep. Confirmed by adding logs "actor/kernel sleeping" to the local copy of Celluloids.rb's sleep().}

---

In server1.rb,

the call to sleep is within server - a class that includes Celluloid.

Thus Celluloid's implementation of sleep overrides the native sleep.

class Server
  include Celluloid::ZMQ

  ...

  def run
    loop { async.handle_message @socket.read }
  end

  def handle_message(message)

        ...

        sleep 60
  end
end

_{Note the log actor sleeping from server1.rb. Log added to Celluloids.rb's sleep()}

This suspends only the current "actor" in Celluloid i.e. only the current "Celluloid thread" handling the client1 sleeps.

---

In server2.rb,

the call to sleep is within a different class DisplayMessage that does NOT include Celluloid.

Thus it is the native sleep itself.

class DisplayMessage
    def self.message(message)

           ...

           sleep 60
    end
end

_{Note the ABSENCE of any actor sleeping log from server2.rb.}

This suspends the current ruby task i.e. the ruby server sleeps (not just a single Celluloid actor).

---

The Fix?

In server2.rb, the appropriate sleep must be explicitly specified.

class DisplayMessage
    def self.message(message)
        puts "Received at #{Time.now.strftime('%I:%M:%S %p')} and message is #{message}"
        ## Intentionally added sleep to test whether Celluloid block the main process for 60 seconds or not.
        if message == 'client-1'
           puts 'Going to sleep now'.red

           # "sleep 60" will invoke the native sleep.
           # Use Celluloid.sleep to support concurrent execution
           Celluloid.sleep 60
        end
    end
end