Timer Objects in Python

Timer objects are used to represent actions that needs to be scheduled to run after a certain instant of time. These objects get scheduled to run on a separate thread that carries out the action. However, the interval that a timer is initialized with might not be the actual instant when the action was actually performed by the interpreter because it is the responsibility of the thread scheduler to actually schedule the thread corresponding to the timer object.

Timer is a sub class of Thread class defined in python. It is started by calling the start() function corresponding to the timer explicitly.

Creating a Timer object

Syntax:

threading.Timer(interval, function, args = None, kwargs = None) 

Create a timer that will run function with arguments args and keyword arguments kwargs, after interval seconds have passed. If args is None (the default) then an empty list will be used. If kwargs is None (the default) then an empty dict will be used.

# Program to demonstrate
# timer objects in python

import threading
def gfg():
    print("GeeksforGeeks\n")

timer = threading.Timer(2.0, gfg)
timer.start()
print("Exit\n")

Output:

Exit
GeeksforGeeks

Explanation: The program above, schedules gfg() function to run after 5 seconds of interval since start() function call.

Cancelling a timer

Syntax:

timer.cancel()

Stop the timer, and cancel the execution of the timer’s action. This will only work if the timer is still in its waiting stage.

# Program to cancel the timer
import threading

def gfg():
    print("GeeksforGeeks\n")

timer = threading.Timer(5.0, gfg)
timer.start()
print("Cancelling timer\n")
timer.cancel()
print("Exit\n")

Output:

Cancelling timer
Exit

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