Can two infinite loops be ran at once?

Question

I want to be able to have two while Trueloops running at the same time. Would this be possible?

I am extremely new to Python, so I do not know how to get round this problem.

This is the code I made:

import time

def infiniteLoop():
    while True:
        print('Loop 1')
        time.sleep(1)

infiniteLoop()

while True:
    print('Loop 2')
    time.sleep(1)

Right now, it just prints a 'Loop 1'

Thanks in advance

Why do you want two separate loops running at the same time? — C_Z_, Apr 25 '16 at 18:03
As you're using `time.sleep` instead of a more complex framework like twisted or tornado, you are tied to use threads. — Luis Masuelli, Apr 25 '16 at 18:09

Brian · Accepted Answer · 2016-04-25T19:11:05.190

15

To run both loops at once, you either need to use two threads or interleave the loops together.

Method 1:

import time
def infiniteloop():
    while True:
        print('Loop 1')
        time.sleep(1)
        print('Loop 2')
        time.sleep(1)

infiniteloop()

Method 2:

import threading
import time

def infiniteloop1():
    while True:
        print('Loop 1')
        time.sleep(1)

def infiniteloop2():
    while True:
        print('Loop 2')
        time.sleep(1)

thread1 = threading.Thread(target=infiniteloop1)
thread1.start()

thread2 = threading.Thread(target=infiniteloop2)
thread2.start()

edited Apr 25 '16 at 19:11

answered Apr 25 '16 at 18:10

Brian

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1

Thanks a lot! Really helped! – RobCoder102 Apr 25 '16 at 18:33
1

it should be `target=infiniteloop1` instead of `target=infiniteloop1()` same with infiniteloop2 – Francisco Apr 25 '16 at 19:10

score 2 · Answer 2 · edited May 23 '17 at 10:33

2

While Brian's answer has you covered, Python's generator functions (and the magic of yield) allow for a solution with two actual loops and without threads:

def a():
    while True:  # infinite loop nr. 1 (kind of)
        print('Loop 1')
        yield

def b():
    for _ in a():    # infinite loop nr. 2
        print('Loop 2')

> b()
Loop 1
Loop 2
Loop 1
Loop 2
....

Here, the two loops in a() and b() are truly interleaved in the sense that in each iteration, execution is passed back and forth between the two.

edited May 23 '17 at 10:33

Community

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answered Apr 25 '16 at 18:52

user2390182

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Very similar to the first method I put ;) – Brian Apr 25 '16 at 18:58
1

Yes and no. Your first solution has only one loop at all (with two `print` statements). – user2390182 Apr 25 '16 at 19:07
func a() has direct impact on func b(), if func a() got stuck in some logic (may be network or db) then func b() code will not execute until func a() unblocks itself – Javed Sayyed Jun 03 '20 at 08:08

Can two infinite loops be ran at once?

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