How to make a Python program wait?

The goal is to make a Python program pause or wait for a specified amount of time during its execution. For example, you might want to print a message, but only after a 3-second delay. This delay could be useful in scenarios where you need to allow time for other processes or events to occur before continuing with the program. Let’s explore different methods to achieve this efficiently.

Using time.sleep()

time.sleep() is used to pause the entire program for a given number of seconds. During this time, the program does nothing and waits, blocking all other operations. It's a simple and blocking delay.

import time
print("Wait for 3 seconds...")
time.sleep(3)
print("Done waiting!")

Output

Explanation: This code pauses the program for 3 seconds. During this time, the program does nothing and waits. After 3 seconds, it continues and prints "Done waiting!". It’s a blocking delay, meaning no other tasks can run during this time.

Using asyncio.run()

This method is used in asynchronous programming. asyncio.sleep() pauses only the current async task without blocking the rest of the program, allowing other tasks to run simultaneously. It’s a non-blocking delay.

import asyncio
print("Wait for 3 seconds...")
asyncio.run(asyncio.sleep(3))
print("Done waiting!")

Output

Explanation: asyncio.run() function runs the asynchronous task and once 3 seconds have passed, it continues to the next line and prints "Done waiting!".

Using threading.Event().wait()

This method pauses only the thread that calls it, without affecting other threads. It’s useful when working with multiple threads and you want to delay or synchronize one of them without blocking everything.

import threading
print("Wait for 3 seconds...")
threading.Event().wait(3)
print("Done waiting!")

Output

Explanation: This code pauses the current thread for 3 seconds. Other threads can continue running during this time. After the delay, it prints "Done waiting!". This is a thread-specific blocking delay.

Using sched.scheduler().enter()

This schedules a function to be executed after a delay. It doesn’t pause the program but registers a task to run later, allowing the rest of the code to continue running in the meantime.

import time
import sched
s = sched.scheduler(time.time, time.sleep)
print("Scheduling task...")
s.enter(3, 1, lambda: print("Executed after 3 seconds!"))
s.run()

Output

Explanation: sched.scheduler(time.time, time.sleep) creates a scheduler using the current time and time.sleep for managing delays. s.enter(3, 1, lambda: print("Executed after 3 seconds!")) schedules a task to run after 3 seconds with priority 1. Finally, s.run() starts the scheduler and executes the task after the delay.