Why does a thread in Python run asynchronously?

Question

Python

Hey!
I have a little gag with Python threads.
I'm using the normal threading module to run a function as a "daemon". when starting the Flask server.
The function itself has logic inside it and a number of functions called by this logic mixed with each other.

It turns out that in the log I see a wild mixture of asynchronous function launches of all the logic that I registered.
Having tested running my function separately in parts and together without entering into threading, everything works fine.

My function does something like this (BE CAREFUL PSEUDOCODE):

def start()
if "файл есть" == 'файл есть':
  while True :
  записываем данные в файл с последней точки (вызываем функцию b1).
else:
 создаем файл (вызываем функцию a1)
 наполняем файл данными (вызываем функцию a2)
 логика проверки даты и времени в записях и т.д. (вызываем функцию a3)
 while True :
    бесконечный цикл наполнения файла последней информацией.(вызываем функцию b1)

flow1 = Thread(target=start, daemon=True)
flow1.start()

What I see in the logs when the stream is started: There is no file -> there is a file creation branch -> the information from the logical branch above appears in the log (the one where the file exists) O_o and starts filling with the latest data. (At the same time, there is a branch of the initial filling of the file with data.) Further, the creation-initial filling function is completed and the usual work of an endless cycle of updating continues.
As a result, the data is stupidly mixed into complete chaos, the logs have the same trouble, and then the cycle fills it normally as I need.

I would like to know how to manage this asynchrony when you have 1 total then 1 thread?
Or is there some nuance when working with internal functions?
I would be grateful for practical examples of solving a similar problem.

Answer 1

The solution is the following. Found the answer in What is the best way to organize two threads of execution inside Flask?
The problem is that Flask already has a flow, and because of this, such parsley as mine happens. It turns out I already have 2 threads and Flask is already somehow spinning them.
Solution: Manually make a separate run() thread and your own

app = Flask(__name__)

@app.route('/')
def hello_world():
    return render_template('index.html')

flow1 = Thread(target=app.run)
flow2 = Thread(target=momowwind, daemon=True)

flow1.start()
flow2.start()

Answer 2

1. Run everything in debug and figure out why
   
2. Refuse flows
   
3. Re-architect solution
   

There are no problems in the pseudocode, so the real code is not like that. Or in additional functions there are cyclic calls.