我有三个脚本,Win7x64上的Python 2.7.9(kivy)。
multiprocessing_1
def Multiprocessing_3():
print "Hohoo!"
import multiprocessing_3
multiprocessing_3.LetseGo()
print "It'se me,",__name__," !!"
if __name__ == "__main__":
import multiprocessing_2
multiprocessing_2.main()
多重处理_2
import multiprocessing
def main():
print "YA!"
import multiprocessing_1
Multiprocessing3 = multiprocessing.Process(target=multiprocessing_1.Multiprocessing_3,args=(''))
Multiprocessing3.start()
multiprocessing_3
def LetseGo():
print "YAHoooooooo!"
我的问题是关于在执行python multiprocessing_1.py
之后抛出的输出:
It'se me, __main__!!
YA!
It'se me, multiprocessing_1!!
It'se me, __parents_main__!!
It'se me, multiprocessing_1!!
Hohoo!
YAHoooooooo!
或在此处查看输出:http://i.imgur.com/ROtLAaZ.png
_1
以__main__
开头,然后导入并调用_2
,然后生成_1.Multiprocessing_3
进程,该进程导入并执行_3.LetseGo()
。
但是,正在发生的事情是_1
实际上运行了四次,而不是我实际预期的两次。
你能告诉我为什么吗?
python大神给出的解决方案
发生这种情况是因为您正在Windows上运行代码,并且Windows需要在子进程中使用re-import your __main__
module(恰好是multiprocessing_1.py
)来执行传递给multiprocessing.Process
的功能。此外,您需要对要在子级中调用的函数Multiprocessing_3
进行腌制,以便将其从父进程发送到子级,并且要在子级中取消选中该函数,需要导入该函数所属的模块,再次是multiprocessing_1
。因此,每个输出的解释是:
It'se me, __main__!! # multiprocessing_1 is imported when you execute it directly.
YA!
It'se me, multiprocessing_1!! # multiprocessing_2.py calls 'import multiprocessing_1'
It'se me, __parents_main__!! # after you call multiprocessing3.start(), the child process needs to re-import the `__main__` module of your script, which is multiprocessing_1.py
It'se me, multiprocessing_1!! # This import happens so that the Multiprocessing_3 function can be unpickled in the child.
Hohoo!
YAHoooooooo!