Changing env back to development mode, the memory leak is likely fixed

config/thin.yml

@@ -7,7 +7,7 @@ max_conns: 1024
 require: []
 
 max_persistent_conns: 512
-environment: production
+environment: development 
 servers: 1
 daemonize: true
 #chdir: /usr/applications/localhash/current

lib/mongo_mapper/clear_dev_memory.rb

@@ -0,0 +1,19 @@
+module MongoMapper
+  class PerRequestMapClear
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      if Rails.configuration.cache_classes
+      else
+        MongoMapper::Document.descendants.each do |m|
+          m.descendants.clear if m.respond_to? :descendants
+        end
+        MongoMapper::Document.descendants.clear
+        MongoMapper::EmbeddedDocument.descendants.clear
+      end
+      @app.call(env)
+    end
+  end
+end