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Python Thread is_alive() Method with Example

Python Thread.is_alive() Method: In this tutorial, we will learn about the is_alive() method of Thread class in Python with its usage, syntax, and examples. By Hritika Rajput Last updated : April 24, 2023

Python Thread.is_alive() Method

The Thread.is_alive() method is an inbuilt method of the Thread class of the threading module, it is used to check whether that thread is alive or not, ie, it is still running or not. This method returns True before the run() starts until just after the run() method is executed.

Module

The following module is required to use is_alive() method:

import threading

Class

The following class is required to use is_alive() method:

from threading import Thread

Syntax

The following is the syntax of is_alive() method:

is_alive()

Parameter(s)

The following are the parameter(s):

• None

Return Value

The return type of this method is <class 'bool'>, it returns True is the thread is alive else returns False.

Example of Thread.is_alive() Method in Python

# 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())

Output

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