Python Sleep Method

First, let's start by defining what Sleep() is?

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What is Python Sleep()?

In Python, Sleep() function is used to delay program execution. It pauses the execution for a given number of seconds and can take floating-point numbers for more precise sleep time. The suspension time may vary. It is not accurate as it uses the system clock, and the accuracy depends on the operating system. 

The system clock is an Advanced Programmable Interrupt Controller (APIC). It works internally by keeping track of CPU cycles and raising Interrupt Requests (IRQs) at programmable intervals. It interrupts whatever code the processor is currently executing, saves its state, and passes control to a piece of code in the operating system.

Python calls select on Linux (and compatibles) and WaitForSingleObjectEx on Windows. Both of these are normally used for I/O, and when called in a blocking way, OS will put the process on hold until the data is available or the time period is expired. It will resume the process once data is available or the time period has expired.

The Sleep() function is defined both in Python 2 and 3, and it only can pause the current thread and not the whole program. 

Checkout:-Python Operators

Python Time Module

Python has a module called time which provides various useful functions related to time tasks. Sleep() is one of the popular functions among them, that suspends the execution of a current thread for a given number of seconds.

Before using the sleep() function, make sure you import the time module. To do so type:

import time

Syntax:

Following is the syntax for sleep() method -

time.sleep(seconds)

It has only one parameter called seconds, which induces delay for that number of seconds in the code execution. This method doesn't return any value.

Let's see a few examples to understand how this function works.

Python time.sleep() examples:

Example 1) Using sleep() function in Python

import time
print("Welcome to Mindmajix Python Tutorial")
time.sleep(2.4)
print(" Print this message after a wait of 2.4 seconds")

Output:

Welcome to Mindmajix Python Tutorial
Print this message after a wait of 2.4 seconds

 

import time
seconds = 5
while seconds > 0:
      print(seconds)
    time.sleep(1)
    seconds = seconds - 1

Output:

5 4 3 2 1

It will print the output with a 1-second delay.

Example 3) Print Date and time with a 1-second interval

import time
while True:
  print("DateTime " + time.strftime("%c"))
  time.sleep(1) ## delays for 1 seconds

Output:

DateTime Tue Jan 5 08:40:18 2021

DateTime Tue Jan 5 08:40:19 2021

DateTime Tue Jan 5 08:40:20 2021

DateTime Tue Jan 5 08:40:21 2021

DateTime Tue Jan 5 08:40:22 2021

And continues until stop.

Example 4) Asking user input for wait time

import time
def sleeper():
while True:
        # Get user input
        num = raw_input('How long to wait: ')
 
        # Try to convert it to a float
        try:
            num = float(num)
        except ValueError:
            print('Please enter in a number.n')
            continue
 
        # Run our time.sleep() command,
        # and show the before and after time
        print('Before: %s' % time.ctime())
        time.sleep(num)
        print('After: %sn' % time.ctime())
 
try:
    sleeper()
except KeyboardInterrupt:
    print('nnKeyboard exception received. Exiting.')
    exit()

output :

How long to wait: 5

Before: Tue Jan 5 08:47:56 2021

After: Tue Jan 5 08:48:01 2021

import time
print ("current time : ",time.ctime())
time.sleep(5)
 print ("after : ",time.ctime())

Current time: 04:37:56
After: 04:38:01

Example 6) Adding different delay time of python sleep()

In Python, you can add different delay times between the execution of the program depending on the required output.

Example,

import time
for k in [2, 2.5, 3, 3.5]:
  print("I will walk for %s" % k, end='')
  print(" kilometres")
  time.sleep(k)

Output:

I will walk for 2 kilometres
I will sleep for 2.5 kilometres
I will sleep for 3 kilometres
I will sleep for 3.5 kilometres

Using asyncio.sleep

Asynchronous capabilities are added to the Python version 3.4 and higher. Asynchronous programming allows you to run various tasks at once. When a task completes, it will notify the main thread. You need to add async and await to use this function.

Example:

import asyncio

async def main():
print('Hello ...')
    await asyncio.sleep(2)
    print('... World!')

asyncio.run(main())

Python Thread Sleep

The time. Sleep () function plays a vital role in multithreading. For single-threaded programs, the function suspends the execution of thread and process. But for multithreaded programs, the sleep function halts the execution of the current thread only rather than the whole process.

Example:

import time
from threading import Thread


class Student(Thread):
    def run(self):
        for x in range(0, 5):
            print(x)
            time.sleep(1)


class Teacher(Thread):
    def run(self):
        for x in range(10, 25):
            print(x)
            time.sleep(5)


print("Staring Student Thread")
Student().start()
print("Starting Teacher Thread")
Teacher().start()
print("Done")

Output:

Starting Student Thread
0
Starting Teacher Thread 
10
Done 
1
2
3
4
11
5

Using event.wait()

The threading module provides an Event() method. When the event is set, the program will break out of the loop immediately.

The working of this function is shown below:

from threading import Event

print('Start Code Execution')

def display():
    print('Welcome to Mindmajix')


Event().wait(10) 
display()

The code is using Event().wait(10).The number 10 is the number of seconds the code will delay to go to the next line.

Frequently Asked Python Interview Questions & Answers

Output:

Start Code Execution
Welcome to Mindmajix

time.sleep()

The sleep() function is defined in the time module.

There are two ways to include it in the program

import time
.sleep(5)   ## suspend execution for five seconds
 
from time import sleep
sleep(5)    	## suspend execution for five seconds
 
sleep() can take floating-point numbers as an argument for more precise sleep time.
 
import time
time.sleep(0.100) ## Wait for 100 milliseconds

Example 1: Simple countdown timer

 
import time
 
seconds = 5
while seconds > 0:
      print(seconds)
    time.sleep(1)
    seconds = seconds - 1

5 4 3 2 1

It will print the output with a 1-second delay.

Example 2: Date and time print with 1-second interval

 
import time
while True:
  print("DateTime " + time.strftime("%c"))
  time.sleep(1) ## delays for 1 seconds

DateTime Tue Sep  5 08:40:18 2017

DateTime Tue Sep  5 08:40:19 2017

DateTime Tue Sep  5 08:40:20 2017

DateTime Tue Sep  5 08:40:21 2017

DateTime Tue Sep  5 08:40:22 2017

And continues until stop.

Example 3: Asking user input for wait time

import time
 
def sleeper():
    while True:
        # Get user input
        num = raw_input('How long to wait: ')
 
        # Try to convert it to a float
        try:
            num = float(num)
        except ValueError:
            print('Please enter in a number.n')
            continue
 
        # Run our time.sleep() command,
        # and show the before and after time
        print('Before: %s' % time.ctime())
        time.sleep(num)
        print('After: %sn' % time.ctime())
 
try:
    sleeper()
except KeyboardInterrupt:
    print('nnKeyboard exception received. Exiting.')
    exit()

How long to wait:  5

Before: Tue Sep  5 08:47:56 2017

After: Tue Sep  5 08:48:01 2017

How It Works:

In Python time.sleep() method blocks thread. If the program is single-threaded, then the process will be also blocked. The substantive part of the sleep operation is wrapped in a Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS block, allowing other threads to continue to execute while the current one sleeps.

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Conclusion:

In this article, we have discussed the sleep () method in Python with a few code examples of how it works. We hope the information shared is helpful for you to put your code to sleep!

If you have any doubts, let us know in the comment section below, our experts will help you with the best possible solution.