Switching web process to Unicorn for more concurrency on Heroku

(see http://collectiveidea.com/blog/archives/2012/11/26/setup-a-high-volume-site-on-heroku-for-free/ )

Gemfile

@@ -3,7 +3,7 @@ source 'https://rubygems.org'
 ruby '1.9.3'
 gem 'rails', '3.2.12'
 gem 'pg'
-gem 'thin'
+gem 'unicorn'
 
 group :assets do
   gem 'jquery-rails', '3.0.1'

Gemfile.lock

@@ -89,7 +89,6 @@ GEM
       capybara (>= 1.1.2)
       cucumber (>= 1.1.3)
       nokogiri (>= 1.5.0)
-    daemons (1.0.10)
     database_cleaner (0.7.1)
     decent_exposure (2.2.0)
     devise (1.5.3)
@@ -196,6 +195,7 @@ GEM
     json (1.8.0)
     jwt (0.1.5)
       multi_json (>= 1.0)
+    kgio (2.8.0)
     launchy (2.1.2)
       addressable (~> 2.3)
     macaddr (1.6.1)
@@ -264,6 +264,7 @@ GEM
       rake (>= 0.8.7)
       rdoc (~> 3.4)
       thor (>= 0.14.6, < 2.0)
+    raindrops (0.10.0)
     rake (10.1.0)
     ransack (0.7.2)
       actionpack (~> 3.0)
@@ -314,10 +315,6 @@ GEM
       sprockets (>= 1.0.2)
     systemu (2.5.2)
     term-ansicolor (1.0.7)
-    thin (1.3.1)
-      daemons (>= 1.0.9)
-      eventmachine (>= 0.12.6)
-      rack (>= 1.0.0)
     thor (0.14.6)
     tilt (1.4.1)
     treetop (1.4.12)
@@ -328,6 +325,10 @@ GEM
     uglifier (1.2.3)
       execjs (>= 0.3.0)
       multi_json (>= 1.0.2)
+    unicorn (4.6.2)
+      kgio (~> 2.6)
+      rack
+      raindrops (~> 0.7)
     uuid (2.3.6)
       macaddr (~> 1.0)
     vcr (2.5.0)
@@ -405,8 +406,8 @@ DEPENDENCIES
   selenium-webdriver
   shoulda-matchers
   simple_form
-  thin
   uglifier
+  unicorn
   vcr
   web_translate_it
   will_paginate (~> 3.0.pre2)

Procfile

@@ -0,0 +1 @@
+web: bundle exec unicorn_rails -p $PORT -c ./config/unicorn.rb

config/unicorn.rb

@@ -0,0 +1,12 @@
+# If you have a very small app you may be able to
+# increase this, but in general 3 workers seems to
+# work best
+worker_processes 3
+
+# Load your app into the master before forking
+# workers for super-fast worker spawn times
+preload_app true
+
+# Immediately restart any workers that
+# haven't responded within 30 seconds
+timeout 30