add rbtrace for production tracing

Gemfile

@@ -193,6 +193,7 @@ gem 'rack-mini-profiler',  git: 'https://github.com/MiniProfiler/rack-mini-profi
 gem 'rack-cors', require: false
 gem 'unicorn', require: false
 gem 'puma', require: false
+gem 'rbtrace', require: false
 
 # perftools only works on 1.9 atm
 group :profile do

Gemfile_rails4.lock

@@ -246,6 +246,7 @@ GEM
     mocha (0.14.0)
       metaclass (~> 0.0.1)
     mock_redis (0.9.0)
+    msgpack (0.5.6)
     multi_json (1.8.2)
     multipart-post (1.2.0)
     mustache (0.99.4)
@@ -336,6 +337,10 @@ GEM
     rb-fsevent (0.9.3)
     rb-inotify (0.9.2)
       ffi (>= 0.5.0)
+    rbtrace (0.4.1)
+      ffi (>= 1.0.6)
+      msgpack (>= 0.4.3)
+      trollop (>= 1.16.2)
     redcarpet (3.0.0)
     redis (3.0.5)
     redis-actionpack (4.0.0)
@@ -441,6 +446,7 @@ GEM
     treetop (1.4.15)
       polyglot
       polyglot (>= 0.3.1)
+    trollop (2.0)
     tzinfo (0.3.38)
     uglifier (2.2.1)
       execjs (>= 0.3.0)
@@ -516,6 +522,7 @@ DEPENDENCIES
   rake
   rb-fsevent
   rb-inotify (~> 0.9)
+  rbtrace
   redcarpet
   redis
   redis-rails!

config/application.rb

@@ -151,5 +151,9 @@ module Discourse
     # absolutly no spot in our app were we use XML as opposed to JSON endpoints
     ActionDispatch::ParamsParser::DEFAULT_PARSERS.delete(Mime::XML)
 
+    if ENV['RBTRACE'] == "1"
+      require 'rbtrace'
+    end
+
   end
 end