The sleep() function suspends (waits) execution of the current string for a given number of seconds.
Python has a module named time which provides several valuable functions to handle with time-related tasks. One of the popular functions among them is sleep().
The sleep() work suspends the execution of the current string for a given number of seconds.
Example 1: Python sleep()
import time print("Printed immediately.") time.sleep(2.4) print("Printed after 2.4 seconds.")
Here’s how this program works:
“Printed immediately” is printed
Suspends (Delays) execution for 2.4 seconds.
“Printed after 2.4 seconds” is printed.
As you can see from the above example, sleep() takes a floating-point number as an argument.
Before Python 3.5, the actual suspension time may be less than the argument specified to the time() function.
Since Python 3.5, the suspension time will be at least the seconds specified.
Example 2: Python create a digital clock
import time while True: localtime = time.localtime() result = time.strftime("%I:%M:%S %p", localtime) print(result) time.sleep(1)
In the above program, we computed and printed the current local time inside the infinite while loop. At that point, the program hangs tight for 1 second. Once more, the current neighborhood time is registered and printed. This procedure goes on.
At the point when you run the program, the yield will be something like:
02:10:50 PM 02:10:51 PM 02:10:52 PM 02:10:53 PM 02:10:54 PM ... .. ...
Here is a slightly modified better version of the above program.
import time while True: localtime = time.localtime() result = time.strftime("%I:%M:%S %p", localtime) print(result, end="", flush=True) print("\r", end="", flush=True) time.sleep(1)
To learn more, visit the digital clock in the Python shell.
Multithreading in Python
Before talking about sleep() in multithreaded programs, let’s talk about processes and threads.
A computer program is a collection of instructions. A process is the execution of those instructions.
A thread is a subset of the process. A process can have one or more threads.
Model 3: Python multithreading
All the projects above in this article are single-threaded programs. Here’s a case of a multithreaded Python program.
import threading def print_hello_three_times(): for i in range(3): print("Hello") def print_hi_three_times(): for i in range(3): print("Hi") t1 = threading.Thread(target=print_hello_three_times) t2 = threading.Thread(target=print_hi_three_times) t1.start() t2.start()
When you run the program, the output will be something like:
Hello Hello Hi Hello Hi Hi
The above program has two threads t1 and t2. These threads are run using t1.start() and t2.start() statements.
Note that, t1 and t2 run concurrently and you might get different outputs.
Visit this page to learn more about Multithreading in Python.
time.sleep() in multithreaded programs
The rest() function suspends execution of the current string for a given number of seconds.
Incase of single-threaded programs, sleep() suspends execution of the string and procedure. In any case, the capacity suspends a string as opposed to the entire procedure in multithreaded programs.
Example 4: sleep() in a multithreaded program
import threading import time def print_hello(): for i in range(4): time.sleep(0.5) print("Hello") def print_hi(): for i in range(4): time.sleep(0.7) print("Hi") t1 = threading.Thread(target=print_hello) t2 = threading.Thread(target=print_hi) t1.start() t2.start()
The above program has two threads. We have used time.sleep(0.5) and time.sleep(0.75) to suspend execution of these two threads for 0.5 seconds and 0.7 seconds respectively.
Recommended Reading: Python time.sleep() sleeps thread
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