Python Thread is_alive()用法及代码示例

Python Thread.is_alive() 方法

Thread.is_alive() 方法是 Python 中线程模块的 Thread 类的内置方法。它使用一个 Thread 对象，并检查该线程是否处于活动状态，即它是否仍在运行。此方法在 run() 开始之前返回 True，直到 run() 方法执行之后。

模块：

    from threading import Thread

用法:

    is_alive()

参数：

• None

返回值：

这个方法的返回类型是<class 'bool'>, 它返回 True 是线程是活着的，否则返回 False 。

例：

# Python program to explain the
# use of is_alive() method

import time
import threading

def thread_1(i):
    time.sleep(5)
    print('Value by Thread 1:', i)

def thread_2(i):
    print('Value by Thread 2:', i)
    
# Creating three sample threads 
thread1 = threading.Thread(target=thread_1, args=(1,))
thread2 = threading.Thread(target=thread_2, args=(2,))

# Before calling the start(), both threads are not alive
print("Is thread1 alive:", thread1.is_alive())
print("Is thread2 alive:", thread2.is_alive())
print()

thread1.start()
thread2.start()
# Since thread11 is on sleep for 5 seconds, it is alive
# while thread 2 is executed instantly

print("Is thread1 alive:", thread1.is_alive())
print("Is thread2 alive:", thread2.is_alive())

输出

Is thread1 alive:False
Is thread2 alive:False

Value by Thread 2:2
Is thread1 alive:True
Is thread2 alive:False
Value by Thread 1:1