问题
Python's threading documentation states:
Other than in the main module, an import should not have the side effect of spawning a new thread and then waiting for that thread in any way. Failing to abide by this restriction can lead to a deadlock if the spawned thread directly or indirectly attempts to import a module.
I'm looking for example code that demonstrates this restriction.
回答1:
I tried this, a module that spawns a thread whose target tries to import sys:
from threading import Thread
def my_target():
import sys
thread = Thread(target=my_target)
thread.start()
thread.join()
When the python interpreter is launched and an attempt to import the module above is made, it indeed freezes.
来源：https://stackoverflow.com/questions/8456389/spawning-a-new-thread-while-importing