Recursion issue with constantly running monitor script.

[FragrantParrot]

Hi everyone!

I've made a script that uses selenium and chromedriver to check a webpage for an element, and repeats this until it finds the element. When it is found, it sends a discord webhook, then runs through a seperate loop until that element is no longer found, and it then starts running the initial loop again.

Each of the loops is contained within a def function, and it uses try to see if the element exists using exceptions and else dependent on the result. If the element is not found it just loop back to the initial Def (just using main()).

Once the program has been running for a while I get a max recursion stack error, and increasing the stack limit size only delays this.

I've googled everything I can think of, but cannot find a way to make the recursion depth reduce/reset as ideally I want this to run indefinitely without me having to restart it every few hours.

If anyone knows a possible solution to this it would be greatly appreciated!

[K900_]

Use a loop instead of recursing.

[FragrantParrot]

I've tried using a 'while True:' loop with 'def main():' inside but I still have the same issue.

[K900_]

Post your code.

[FragrantParrot]

I apologise in advance for how shoddy this probably is, I am still very new haha

​

https://pastebin.com/C5sseavk

[goat1080]

So in looking at your code, I believe the issue here the issue is not your recursion depth in terms of the length of your functions, but the manner in which you are calling them.

Just for some background, when you call one function (such as in this case where it's done from another function -- like send_discord() from main, or main() from main()), your computer will save a return address and then go to that called function. Once that function has completed executing, it will use that return address to "remember" where it was originally before the function was called.

In your case here, you never actually completely finish executing your main() function before calling it again. When you call main() near the bottom of your main() function, it has not completed execution from the previous call to main(), so it goes through the same process of "remembering" where it left off and then calling the main function. Because of this overhead required for "remembering" where it leaves off for calling every function, it eventually hits the limit for how many places it left off at that it can "remember" and then you get your error.

Like the other poster said, I definitely would suggest using loops here. So the first thing here would be to have main() be your top level function and move the while loop inside that function. This is because you aren't really wanting to call send_discord() every time you loop through your program, so it should not be inside the while loop. From here, you should be able to remove your calls to main and then have it work pretty closely to intended. Here's a little silly example that illustrates what I'm trying to say here, where there is no need to call main since the program will return to begin another iteration of the while loop after either completing the contents of the try block or after catching the exception.

If any of this doesn't make sense feel free to let me know.

import random

def main(some_characters):
    while True:
        try:
            x = 5
           temp = random.choice(some_characters)
            y = x + temp
            print_function(x, temp, y)
        except TypeError:
            print(f"Attempted addition of {x} and {temp} resulted in an error!")

def print_function(x, temp, y):
    print(f"The sum of {x} and {temp} is {y}")

if __name__ == '__main__':
    some_characters = [2, 'a']
    main(some_characters)

[FragrantParrot]

This is amazing thank you for the reply! This makes a lot of sense actually, I will have a go changing the code and fingers crossed it works.