Remove allow_concurrency as a flag

The flag was mainly used to add a Rack::Lock middleware to
the stack, but the only scenario the lock is desired is in
development.

If you are deploying on a not-threaded server, the Rack::Lock
does not provide any benefit since you don't have concurrent
accesses. On the other hand, if you are on a threaded server,
you don't want the lock, since it defeats the purpose of using
a threaded server.

If there is someone out there, running on a thread server
and does want a lock, it can be added to your environment
as easy as: `use Rack::Lock`

1 files changed, 1 insertions, 3 deletions

diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 7dffe91bb9..77d89f0cb9 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -5,7 +5,7 @@ require 'rails/engine/configuration'
 module Rails
   class Application
     class Configuration < ::Rails::Engine::Configuration
-      attr_accessor :allow_concurrency, :asset_host, :asset_path, :assets, :autoflush_log,
+      attr_accessor :asset_host, :asset_path, :assets, :autoflush_log,
                     :cache_classes, :cache_store, :consider_all_requests_local, :console,
                     :eager_load, :exceptions_app, :file_watcher, :filter_parameters,
                     :force_ssl, :helpers_paths, :logger, :log_formatter, :log_tags,
@@ -20,7 +20,6 @@ module Rails
       def initialize(*)
         super
         self.encoding = "utf-8"
-        @allow_concurrency             = false
         @consider_all_requests_local   = false
         @filter_parameters             = []
         @helpers_paths                 = []
@@ -99,7 +98,6 @@ module Rails
         @preload_frameworks = true
         @cache_classes = true
         @eager_load = true
-        @allow_concurrency = true
         self
       end