fix

config/initializers/session_extenstions.rb

@@ -0,0 +1,33 @@
+#coding=utf-8
+
+module  SessionExtenstions
+
+  module EntryExtension
+    def compressed?
+      @compressed
+    end
+
+    def value
+      if @value
+        begin
+          Marshal.load(compressed? ? Zlib::Inflate.inflate(@value) : @value)
+        rescue TypeError
+          compressed? ? Zlib::Inflate.inflate(@value) : @value
+        end
+      end
+    end
+
+    def size
+      if @value.nil?
+        0
+      else
+        @value.bytesize
+      end
+    end
+  end
+
+
+end
+
+ActiveSupport::Cache::Entry.const_set("DEFAULT_COMPRESS_LIMIT", 1)
+ActiveSupport::Cache::Entry.send(:prepend, SessionExtenstions::EntryExtension)