Merge pull request #132 from ruby-concurrency/actress

Adding features to Actors

Author: Petr Chalupa

doc/actress/celluloid_benchmark.rb doc/actor/celluloid_benchmark.rbdoc/actress/celluloid_benchmark.rb renamed to doc/actor/celluloid_benchmark.rb

@@ -1,9 +1,13 @@
 require 'benchmark'
-require 'concurrent/actress'
-Concurrent::Actress.i_know_it_is_experimental!
+require 'concurrent/actor'
+Concurrent::Actor.i_know_it_is_experimental!
+
 require 'celluloid'
 require 'celluloid/autostart'
 
+# require 'stackprof'
+# require 'profiler'
+
 logger                          = Logger.new($stderr)
 logger.level                    = Logger::INFO
 Concurrent.configuration.logger = lambda do |level, progname, message = nil, &block|
@@ -30,26 +34,26 @@ def counting(count, ivar)
       ivar.set count
     end
   end
-end
+end if defined? Celluloid
 
 threads = []
 
+# Profiler__.start_profile
+# StackProf.run(mode:     :cpu,
+#               interval: 10,
+#               out:      File.join(File.dirname(__FILE__), 'stackprof-cpu-myapp.dump')) do
 Benchmark.bmbm(10) do |b|
   [2, adders_size, adders_size*2, adders_size*3].each do |adders_size|
 
-    b.report(format('%5d %4d %s', ADD_TO*counts_size, adders_size, 'actress')) do
+    b.report(format('%5d %4d %s', ADD_TO*counts_size, adders_size, 'concurrent')) do
       counts = Array.new(counts_size) { [0, Concurrent::IVar.new] }
       adders = Array.new(adders_size) do |i|
-        Concurrent::Actress::AdHoc.spawn("adder#{i}") do
+        Concurrent::Actor::AdHoc.spawn("adder#{i}") do
           lambda do |(count, ivar)|
-            if count.nil?
-              terminate!
+            if count < ADD_TO
+              adders[(i+1) % adders_size].tell [count+1, ivar]
             else
-              if count < ADD_TO
-                adders[(i+1) % adders_size].tell [count+1, ivar]
-              else
-                ivar.set count
-              end
+              ivar.set count
             end
           end
         end
@@ -65,32 +69,38 @@ def counting(count, ivar)
 
       threads << Thread.list.size
 
-      adders.each { |a| a << [nil, nil] }
+      adders.each { |a| a << :terminate! }
     end
 
-    b.report(format('%5d %4d %s', ADD_TO*counts_size, adders_size, 'celluloid')) do
-      counts = []
-      counts_size.times { counts << [0, Concurrent::IVar.new] }
+    if defined? Celluloid
+      b.report(format('%5d %4d %s', ADD_TO*counts_size, adders_size, 'celluloid')) do
+        counts = []
+        counts_size.times { counts << [0, Concurrent::IVar.new] }
 
-      adders = []
-      adders_size.times do |i|
-        adders << Counter.new(adders, i)
-      end
+        adders = []
+        adders_size.times do |i|
+          adders << Counter.new(adders, i)
+        end
 
-      counts.each_with_index do |count, i|
-        adders[i % adders_size].counting *count
-      end
+        counts.each_with_index do |count, i|
+          adders[i % adders_size].counting *count
+        end
 
-      counts.each do |count, ivar|
-        raise unless ivar.value >= ADD_TO
-      end
+        counts.each do |count, ivar|
+          raise unless ivar.value >= ADD_TO
+        end
 
-      threads << Thread.list.size
+        threads << Thread.list.size
 
-      adders.each(&:terminate)
+        adders.each(&:terminate)
+      end
     end
   end
 end
+# end
+# Profiler__.stop_profile
 
 p threads
 
+# Profiler__.print_profile $stdout
+

doc/actress/examples.in.rb doc/actor/examples.in.rbdoc/actress/examples.in.rb renamed to doc/actor/examples.in.rb

@@ -0,0 +1,3 @@
+
+
+

doc/actor/examples.out.rb

@@ -0,0 +1,2 @@
+require 'concurrent/actor'
+Concurrent::Actor.i_know_it_is_experimental!

doc/actress/format.rb doc/actor/format.rbdoc/actress/format.rb renamed to doc/actor/format.rb

@@ -0,0 +1,133 @@
+# Actor model
+
+-  Light-weighted.
+-  Inspired by Akka and Erlang.
+-  Modular.
+
+Actors are sharing a thread-pool by default which makes them very cheap to create and discard.
+Thousands of actors can be created, allowing you to break the program into small maintainable pieces,
+without violating the single responsibility principle.
+
+## What is an actor model?
+
+[Wiki](http://en.wikipedia.org/wiki/Actor_model) says:
+The actor model in computer science is a mathematical model of concurrent computation
+that treats _actors_ as the universal primitives of concurrent digital computation:
+in response to a message that it receives, an actor can make local decisions,
+create more actors, send more messages, and determine how to respond to the next
+message received.
+
+## Why?
+
+Concurrency is hard this is one of many ways how to simplify the problem.
+It is simpler to reason about actors than about locks (and all their possible states).
+
+## How to use it
+
+{include:file:doc/actor/quick.out.rb}
+
+## Messaging
+
+Messages are processed in same order as they are sent by a sender. It may interleaved with
+messages form other senders though. There is also a contract in actor model that
+messages sent between actors should be immutable. Gems like
+
+- [Algebrick](https://github.com/pitr-ch/algebrick) - Typed struct on steroids based on
+  algebraic types and pattern matching
+- [Hamster](https://github.com/hamstergem/hamster) - Efficient, Immutable, Thread-Safe
+  Collection classes for Ruby
+
+are very useful.
+
+### Dead letter routing
+
+see {AbstractContext#dead_letter_routing} description:
+
+> {include:Actor::AbstractContext#dead_letter_routing}
+
+## Architecture
+
+Actors are running on shared thread poll which allows user to create many actors cheaply.
+Downside is that these actors cannot be directly used to do IO or other blocking operations.
+Blocking operations could starve the `default_task_pool`. However there are two options:
+
+- Create an regular actor which will schedule blocking operations in `global_operation_pool`
+  (which is intended for blocking operations) sending results back to self in messages.
+- Create an actor using `global_operation_pool` instead of `global_task_pool`, e.g.
+  `AnIOActor.spawn name: :blocking, executor: Concurrent.configuration.global_operation_pool`.
+
+Each actor is composed from 4 parts:
+
+### {Reference}
+{include:Actor::Reference}
+
+### {Core}
+{include:Actor::Core}
+
+### {AbstractContext}
+{include:Actor::AbstractContext}
+
+### {Behaviour}
+{include:Actor::Behaviour}
+
+## Speed
+
+Simple benchmark Actor vs Celluloid, the numbers are looking good
+but you know how it is with benchmarks. Source code is in
+`examples/actor/celluloid_benchmark.rb`. It sends numbers between x actors
+and adding 1 until certain limit is reached.
+
+Benchmark legend:
+
+- mes.  - number of messages send between the actors
+- act.  - number of actors exchanging the messages
+- impl. - which gem is used
+
+### JRUBY
+
+    Rehearsal --------------------------------------------------------
+    50000    2 concurrent 24.110000   0.800000  24.910000 (  7.728000)
+    50000    2 celluloid  28.510000   4.780000  33.290000 ( 14.782000)
+    50000  500 concurrent 13.700000   0.280000  13.980000 (  4.307000)
+    50000  500 celluloid  14.520000  11.740000  26.260000 ( 12.258000)
+    50000 1000 concurrent 10.890000   0.220000  11.110000 (  3.760000)
+    50000 1000 celluloid  15.600000  21.690000  37.290000 ( 18.512000)
+    50000 1500 concurrent 10.580000   0.270000  10.850000 (  3.646000)
+    50000 1500 celluloid  14.490000  29.790000  44.280000 ( 26.043000)
+    --------------------------------------------- total: 201.970000sec
+    
+     mes. act.      impl.      user     system      total        real
+    50000    2 concurrent  9.820000   0.510000  10.330000 (  5.735000)
+    50000    2 celluloid  10.390000   4.030000  14.420000 (  7.494000)
+    50000  500 concurrent  9.880000   0.200000  10.080000 (  3.310000)
+    50000  500 celluloid  12.430000  11.310000  23.740000 ( 11.727000)
+    50000 1000 concurrent 10.590000   0.190000  10.780000 (  4.029000)
+    50000 1000 celluloid  14.950000  23.260000  38.210000 ( 20.841000)
+    50000 1500 concurrent 10.710000   0.250000  10.960000 (  3.892000)
+    50000 1500 celluloid  13.280000  30.030000  43.310000 ( 24.620000) (1)
+
+### MRI 2.1.0
+
+    Rehearsal --------------------------------------------------------
+    50000    2 concurrent  4.640000   0.080000   4.720000 (  4.852390)
+    50000    2 celluloid   6.110000   2.300000   8.410000 (  7.898069)
+    50000  500 concurrent  6.260000   2.210000   8.470000 (  7.400573)
+    50000  500 celluloid  10.250000   4.930000  15.180000 ( 14.174329)
+    50000 1000 concurrent  6.300000   1.860000   8.160000 (  7.303162)
+    50000 1000 celluloid  12.300000   7.090000  19.390000 ( 17.962621)
+    50000 1500 concurrent  7.410000   2.610000  10.020000 (  8.887396)
+    50000 1500 celluloid  14.850000  10.690000  25.540000 ( 24.489796)
+    ---------------------------------------------- total: 99.890000sec
+    
+     mes. act.      impl.      user     system      total        real
+    50000    2 concurrent  4.190000   0.070000   4.260000 (  4.306386)
+    50000    2 celluloid   6.490000   2.210000   8.700000 (  8.280051)
+    50000  500 concurrent  7.060000   2.520000   9.580000 (  8.518707)
+    50000  500 celluloid  10.550000   4.980000  15.530000 ( 14.699962)
+    50000 1000 concurrent  6.440000   1.870000   8.310000 (  7.571059)
+    50000 1000 celluloid  12.340000   7.510000  19.850000 ( 18.793591)
+    50000 1500 concurrent  6.720000   2.160000   8.880000 (  7.929630)
+    50000 1500 celluloid  14.140000  10.130000  24.270000 ( 22.775288) (1)
+
+*Note (1):* Celluloid is using thread per actor so this bench is creating about 1500
+native threads. Actor is using constant number of threads.

doc/actor/init.rb

@@ -1,7 +1,6 @@
-class Counter
+class Counter < Concurrent::Actor::Context
   # Include context of an actor which gives this class access to reference and other information
-  # about the actor, see CoreDelegations.
-  include Concurrent::Actress::Context
+  # about the actor, see PublicDelegations.
 
   # use initialize as you wish
   def initialize(initial_value)
@@ -10,16 +9,11 @@ def initialize(initial_value)
 
   # override on_message to define actor's behaviour
   def on_message(message)
-    case message
-    when Integer
+    if Integer === message
       @count += message
-    when :terminate
-      terminate!
-    else
-      raise 'unknown'
     end
   end
-end
+end #
 
 # Create new actor naming the instance 'first'.
 # Return value is a reference to the actor, the actual actor is never returned.
@@ -35,7 +29,7 @@ def on_message(message)
 counter.ask(0).value
 
 # Terminate the actor.
-counter.tell(:terminate)
+counter.tell(:terminate!)
 # Not terminated yet, it takes a while until the message is processed.
 counter.terminated?
 # Waiting for the termination.
@@ -52,22 +46,18 @@ def on_message(message)
 
 
 # Lets define an actor creating children actors.
-class Node
-  include Concurrent::Actress::Context
-
+class Node < Concurrent::Actor::Context
   def on_message(message)
     case message
     when :new_child
-      spawn self.class, :child
+      Node.spawn :child
     when :how_many_children
       children.size
-    when :terminate
-      terminate!
     else
       raise 'unknown'
     end
   end
-end
+end #
 
 # Actors are tracking parent-child relationships
 parent = Node.spawn :parent