Switched from Thin to Puma webserver.

Threads on Heroku have been limited to 1.

We need to test the rails app and make sure it is thread safe

See more info at https://devcenter.heroku.com/articles/deploying-rails-applications-with-the-puma-web-server

Gemfile

@@ -9,7 +9,8 @@ gem 'google-api-client',  '~> 0.6.4'
 gem 'devise',    '~> 3.2.4'          # For managing authentication
 gem 'figaro',     '~> 0.7.0'                    # Managing environment variables
 gem 'github_api' #, '~> 0.11.1' # to pull in the curriculum files
-gem 'thin', '~> 1.6.1' # to use the "thin" webserver instead of webrick
+gem 'puma',     '~> 2.16.0'  # to use the "puma" webserver instead of webrick
+gem 'rack-timeout', '~> 0.3.2'
 gem 'redcarpet', '~> 3.0.0' # to render the curriculum's .md files as html
 gem 'will_paginate', '~> 3.0.5' # to paginate student lists
 gem 'protected_attributes', '~> 1.0.5'

Gemfile.lock

@@ -61,7 +61,6 @@ GEM
     commonjs (0.2.7)
     css_parser (1.3.7)
       addressable
-    daemons (1.2.3)
     database_cleaner (1.2.0)
     debug_inspector (0.0.2)
     descendants_tracker (0.0.4)
@@ -76,7 +75,6 @@ GEM
     disqus (1.0.4)
       json
     erubis (2.7.0)
-    eventmachine (1.0.9.1)
     execjs (2.6.0)
     extlib (0.9.16)
     factory_girl (4.3.0)
@@ -172,11 +170,13 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
+    puma (2.16.0)
     quiet_assets (1.0.3)
       railties (>= 3.1, < 5.0)
     rack (1.5.5)
     rack-test (0.6.3)
       rack (>= 1.0)
+    rack-timeout (0.3.2)
     rails (4.0.2)
       actionmailer (= 4.0.2)
       actionpack (= 4.0.2)
@@ -217,7 +217,7 @@ GEM
       sass (~> 3.2.2)
       sprockets (~> 2.8, < 3.0)
       sprockets-rails (~> 2.0)
-    selenium-webdriver (2.50.0)
+    selenium-webdriver (2.51.0)
       childprocess (~> 0.5)
       multi_json (~> 1.0)
       rubyzip (~> 1.0)
@@ -243,10 +243,6 @@ GEM
     therubyracer (0.12.2)
       libv8 (~> 3.16.14.0)
       ref
-    thin (1.6.4)
-      daemons (~> 1.0, >= 1.0.9)
-      eventmachine (~> 1.0, >= 1.0.4)
-      rack (~> 1.0)
     thor (0.19.1)
     thread_safe (0.3.5)
     tilt (1.4.1)
@@ -297,15 +293,16 @@ DEPENDENCIES
   premailer-rails
   protected_attributes (~> 1.0.5)
   pry
+  puma (~> 2.16.0)
   quiet_assets (~> 1.0.2)
+  rack-timeout (~> 0.3.2)
   rails (= 4.0.2)
   rails_12factor (~> 0.0.2)
   redcarpet (~> 3.0.0)
   rspec-rails (~> 2.14.1)
   sass-rails (~> 4.0.1)
   simple_form (~> 3.0.1)
   therubyracer (~> 0.12.2)
-  thin (~> 1.6.1)
   twitter-bootstrap-rails (= 2.2.6)
   uglifier (>= 1.0.3)
   will_paginate (~> 3.0.5)

Procfile

@@ -0,0 +1 @@
+web: bundle exec puma -C config/puma.rb

config/initializers/timeout.rb

@@ -0,0 +1,3 @@
+require 'rack-timeout'
+
+Rack::Timeout.timeout = 20

config/puma.rb

@@ -0,0 +1,15 @@
+workers Integer(ENV['WEB_CONCURRENCY'] || 2)
+threads_count = Integer(ENV['MAX_THREADS'] || 5)
+threads threads_count, threads_count
+
+preload_app!
+
+rackup      DefaultRackup
+port        ENV['PORT']     || 3000
+environment ENV['RACK_ENV'] || 'development'
+
+on_worker_boot do
+  # Worker specific setup for Rails 4.1+
+  # See: https://devcenter.heroku.com/articles/deploying-rails-applications-with-the-puma-web-server#on-worker-boot
+  ActiveRecord::Base.establish_connection
+end