multithreading - Python and threading: Why does "large" list entity get lost when accessing from other method? -

a large entity (list) created in 1 method (foo) , bound self.result. attempt access entity in second method (transmit) fails starting @ size (something between 150,000 , 155,000 characters in list). printing (print self.result) inside transmit leaves me none. guess important: self.foo directly called in separate thread.
please help. how such "large" entity separate thread main thread without such limitation?

...      def apply(self):         self.get_data()         self.start_foo_thread()      def start_foo_thread(self):         self.foo_thread = threading.thread(target=self.foo)         self.foo_thread.daemon = true         self.progressbar.start()         self.foo_thread.start()         self.master.after(20, self.check_foo_thread)      def check_foo_thread(self):         if self.foo_thread.is_alive():             self.master.after(20, self.check_foo_thread)         else:             self.progressbar.stop()      def foo(self):          s = self.stringinput         n = self.numberinput         list = multiply_str_into_list(s, n)         self.result = list_to_text(list)         print self.result # output not none       def transmit(self):         print self.result # output none more 155,000 characters in list         return self.result  def multiply_str_into_list(string, n): #takes string , multiplies n , writes list     n_string = []     in range(0,n):         n_string.append(string)     return n_string  def list_to_text(list): #takes list input , joins str each list item on new line     = '\n'.join(list)     return 

you don't provide enough information reproduce problem, let alone debug it, guess @ point, doing this:

self.result = self.result.append(x) 

since .append() modifies list in place, , returns none, clobber reference list. needn't .append() either -- of methods mutate lists return none.

as why happening @ size, perhaps have code above triggered @ size, or else red herring.