"warning: instance variable @safe_initialization not initialized"

Author: amatsuda

lib/concurrent/synchronization/object.rb

@@ -79,7 +79,7 @@ def self.new(*)
       end
 
       def self.safe_initialization?
-        @safe_initialization || (superclass.respond_to?(:safe_initialization?) && superclass.safe_initialization?)
+        (defined?(@safe_initialization) && @safe_initialization) || (superclass.respond_to?(:safe_initialization?) && superclass.safe_initialization?)
       end
 
       # For testing purposes, quite slow.