python之多处理映射引发异常

我有这个使用多处理的简单 map 示例。但即使这样我也无法正确运行。

import multiprocessing 
 
p = multiprocessing.Pool() 
 
rere = range(50) 
print p.map(lambda x: x+1, rere) 

它将打印这个异常:

Exception in thread Thread-3: 
Traceback (most recent call last): 
  File "/usr/lib/python2.7/threading.py", line 808, in __bootstrap_inner 
    self.run() 
  File "/usr/lib/python2.7/threading.py", line 761, in run 
    self.__target(*self.__args, **self.__kwargs) 
  File "/usr/lib/python2.7/multiprocessing/pool.py", line 342, in _handle_tasks 
    put(task) 
PicklingError: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed 

并且无法用 Ctrl+C 终止。

我应该如何修复我的示例以使其正常工作？