Python多线程下的_strptime问题

由于Python的datetime和time中的_strptime方法不支持多线程，运行时会报错：

import datetime
import thread
import time

def f():
    datetime.datetime.strptime("20100101","%Y%m%d")

for _ in xrange(3):
    thread.start_new_thread(f, ())
time.sleep(3)

Unhandled exception in thread started by <function f at 0x2b52c24e66e0>
Traceback (most recent call last):
  File "test.py", line 7, in f
    datetime.datetime.strptime("20100101","%Y%m%d")
AttributeErrorUnhandled exception in thread started by <function f at 0x2b52c24e66e0>:
Traceback (most recent call last):
  File "test.py", line 7, in f
_strptime
    datetime.datetime.strptime("20100101","%Y%m%d")
AttributeError: _strptime

参考 http://bugs.python.org/issue7980

在源文件中可以fix这个bug，不过对于用户来说，还是在使用的时候加锁吧。。

c = threading.RLock()
def f():
    with c:
        datetime.datetime.strptime("20100101","%Y%m%d")