Run a function that takes user input in background to main

Question

I am a beginner in python and this question may seem redundant but I have not been able to solve this. I want to run a function that takes a user input and keeps waiting for user input in background while main function keeps running.

The function takes parameters as arguments that are dependent on the main function. Also, if the user doesn't give any input, then the code below that function must execute.

I have been trying to use threading concept but found no success. The code is as follows:

import sys
import time
import logging
import threading
event_handler = Handler()
observer = watchdog.observers.Observer()
observer.schedule(event_handler, path, recursive=True)
observer.start()
try:
    while True:
        time.sleep(1)
except KeyboardInterrupt:
    observer.stop()
observer.join()

import watchdog.events
import watchdog.observers
import queue
import itertools
from copy import deepcopy
class Handler(watchdog.events.PatternMatchingEventHandler):
    def __init__(self):
        watchdog.events.PatternMatchingEventHandler.__init__(self, patterns=['*.txt'],
                                                         ignore_directories=True, case_sensitive=False)

    def function_to_be_threaded(self,user_input,arg1,arg2,val):
        user_input[0] = input('Enter information')
        ...
        ...
        val[0] = ...

    def on_created(self,):
        ...
        ...
        arg1 = ...
        arg2 = ...
        user_input = [None]
        val = [None]
        flag = False
        t = threading.Thread(target = function_to_be_threaded, args = (user_input,arg1,arg2,val,))
        t.daemon = True
        t.start()
        for i in range(1,10):
            time.sleep(1)
            if(user_input[0] is not None):
                result = val[0]
                ...
                flag = True
                break
        if(not flag):
            ...
            ...
    
        ... #this part should always execute irrespective of flag
        ...

But the code keeps waiting for user input and crashes after some time.

Does this answer your question? [How to use threading to get user input realtime while main still running in python](https://stackoverflow.com/questions/31768865/how-to-use-threading-to-get-user-input-realtime-while-main-still-running-in-pyth) — Yoshikage Kira, May 19 '21 at 06:46
@Goion I checked this. But I am not able to solve using this. — rb173, May 19 '21 at 06:51
You must be doing something other than what you posted, because that code works perfectly for me. — Tim Roberts, May 19 '21 at 07:01

score 1 · Answer 1 · answered May 19 '21 at 09:49

1

I used this method yesterday too, but it somehow didn't work. I just looked it up, and found that every tutorial had

t = threading.Thread(target=target_function)
t.start()
t.join()

But I didn't use the .join() method, and you neither. Maybe this is the Problem? Also please send me feedback.

answered May 19 '21 at 09:49

Xyndra

110
1
11

1

I have tried with .join() as well. It is just that the code doesn't crash. But it still keeps waiting for user input and doesn't execute further code in spite of threading. – rb173 May 19 '21 at 10:41

Run a function that takes user input in background to main

1 Answers1