added EMBED_CLOCKWORK so users can embed clockwork scheduling inside another process

config/application.rb

@@ -121,6 +121,18 @@ module Discourse
     # So open id logs somewhere sane
     config.after_initialize do
       OpenID::Util.logger = Rails.logger
+
+      if ENV['EMBED_CLOCKWORK']
+        puts ">> Running clockwork in background thread"
+        require_relative "clock"
+
+        Thread.new do
+          Clockwork.run
+        end
+      end
+
     end
+
+
   end
 end

config/clock.rb

@@ -1,6 +1,8 @@
 require 'clockwork'
-require_relative 'boot'
-require_relative 'environment'
+unless ENV['EMBED_CLOCKWORK']
+  require_relative 'boot'
+  require_relative 'environment'
+end
 
 # These are jobs you should run on a regular basis to make your
 # forum work properly.

docs/INSTALL.md

@@ -34,6 +34,14 @@ And you can try to set up following components manually on it:
   - Run a clockwork process for enqueing scheduled jobs
   - Run several Rails processes, preferably behind a proxy like Nginx.
 
+---
+
+# Low memory installs
+
+- Clockwork can run inside your web server, if you launch the your web server with EMBED_CLOCKWORK=1, 
+   clockwork will run in a backgroud thread. As clockwork itself only performs scheduling, it will have
+   very little impact on performance
+
 [1]: https://github.com/discourse/discourse/blob/master/docs/INSTALL-ubuntu.md
 [2]: https://github.com/discourse/discourse/blob/master/docs/HEROKU.md