如何不等待线程在Python中完成 [英] How NOT to wait for a thread to finish in Python

问题描述

在此问题中，他实际上问了一些我想要的东西.答案是删除括号.但是，如果删除括号，则将无法为函数传递参数.

In this question, he actually asked something like what I want. Except that the answer was to remove the parentheses. However if I remove the parentheses, then I'll not be able to pass arguments for my functions.

如何在不等待的情况下执行以下简单代码:

How can I do the following simple code without waiting:

from time import sleep
import threading

def whatever(i):
  sleep(5)
  print("Hey! It's me number " + str(i))

for i in range(3):
  t = threading.Thread(target=whatever(i))
  t.start()

所需的输出将是

Hey! It's me number 0
Hey! It's me number 1
Hey! It's me number 2

全部同时打印

推荐答案

在文档中，target应该是可调用的:

target是run()方法要调用的可调用对象

target is the callable object to be invoked by the run() method

您没有将函数传递给target，而是传递了函数的返回值，因此该函数在将其传递给threading.Thread后立即运行，而不是在调用t.start()时运行.

You are not passing your function to target, you are passing the return value of your function, so the function runs as soon as you pass it to threading.Thread, not when you call t.start().

您应该使用args参数为可调用对象指定参数.

You should be using the args parameter to specify arguments to your callable.

只需更改此行:

 t = threading.Thread(target=whatever(i))

到

t = threading.Thread(target=whatever, args=(i,))

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