[FIXED] Jupyter is busy (stuck) randomly when input() is executed inside while statement

Issue

Has anyone ever had a problem that Jupyter is busy (stuck) when executing input() inside the while statement? The problem is randomly happening to me. Sometimes the command box is prompted next to the cell, and sometimes the input() box never prompts.

Here is the simpler version of my code:

from IPython.display import clear_output

class game_quit(Exception):
    def _render_traceback_(self):
        pass
    
def the_game(player_status = "Offering"):
    while True:
        clear_output()
        print("The Game", flush = True)
        print(f"Status: {player_status}", flush = True)
        if (player_status == "Offering") or (player_status == "Wrong input!"):
            play_offer = input("Would you like to play the game (Y or N)? ")
            if play_offer.upper() == "Y":
                player_status = "Playing"
                play_accepted = True
                clear_output()
                break
            elif play_offer.upper() == "N":
                play_accepted = False
                clear_output()
                break
            else:
                player_status = "Wrong input!"
                clear_output()
                continue
        else:
            player_status = "Playing"
            play_accepted = True
            clear_output()
            break
    while play_accepted:
        the_play(player_status)
    else:
        raise game_quit()

def the_play(player_status):
    while True:
        clear_output()
        print("The Game", flush = True)
        print(f"Status: {player_status}", flush = True)
        pet_offer = input("Do you want to go with a (D)og, a (C)at, or a (P)arakeet? ")
        if pet_offer.upper() == "D":
            player_pet = "Dog"
            clear_output()
            break
        elif pet_offer.upper() == "C":
            player_pet = "Cat"
            clear_output()
            break
        elif pet_offer.upper() == "P":
            player_pet = "Parakeet"
            clear_output()
            break
        else:
            player_status = "Wrong input!"
            clear_output()
            continue
    while pet_offer:
        clear_output()
        print(f"Your companion is a {player_pet}", flush = True)
        play_again = input("Would you like to continue playing the game (Y or N)? ")
        if play_again.upper() == "Y":
            play_continue = True
            clear_output()
            break
        elif play_again.upper() == "N":
            play_continue = False
            clear_output()
            break
        else:
            player_status = "Wrong input!"
            clear_output()
            continue
    if play_continue:
        player_status = "Playing"
        the_game(player_status)
    else:
        raise game_quit()

Step to reproduce the problem:

1. Execute the code.

the_game()

2. The user wants to play the game.

play_offer = input("Would you like to play the game (Y or N)? ")

3. The user chooses his pet.

pet_offer = input("Do you want to go with a (D)og, a (C)at, or a (P)arakeet? ")

4. The user wants to replay the game.

play_again = input("Would you like to continue playing the game (Y or N)? ")

5. The user should expect the text box to choose his pet.

pet_offer = input("Do you want to go with a (D)og, a (C)at, or a (P)arakeet? ")

6. A

The problem:
The text box is not showing. The running code is stuck there.

6. B

But sometimes:
The text box is showing, and the user can choose his pet.

So far, my only solution is to restart the kernel. Has anyone had a solution for this kind of problem?

Regards,
Ade

Solution

Someone gave me an insight. The problem is because clear_output() asynchronous problem. Then I created this function:

from time import sleep
from IPython.display import clear_output

def refresh_screen():
    clear_output()
    sleep(0.02)

and replaced all clear_output() with refresh_screen() in my code. The problem is gone. A little delay solved the problem.

Answered By - Ade Syseng