如何等待 function 在 while 循环内完成？

Question

A simplified structure of my code is below. I'm calling a function from inside a while loop, but the function called form inside that function needs to finish before the next iteration of the while loop. I've tried threading as below but it will give me RuntimeError: main thread is not in main loop .

What would be a good way to go about this?

def mainFunction():
   #some code

def secondFunction():
   #some code
   mainFunction()

def thirdfunction():
   #some code
   def funcInFunc():
      #some code 
      secondFunction()

def fourthFunction():
   #some code
   while [condition]:
      #some code
      #here calling funcInFunc() inside thirdFunction()
      funcInFunc()
      #need to wait for mainFunction() called from secondFunction() called from funcInFunc() to 
finish before next iteration of this while loop 
 
      #WAIT FOR mainFunction() TO FINISH
      #Tried but didn't work:
      t = threading.Thread(target=funcInFunc, args=())   
      t.start()
      while t_isAlive():
         pass

Answer 1

Hard to do it without a real example. So I try to explain my thoughts with your pseudo-code. I would use a global _flag variable, to authorize the following of the thread.

def mainFunction():
   #some code
   # end of mainFunction
   _flag = 0

def secondFunction():
   #some code
   mainFunction()

def thirdfunction():
   #some code
   def funcInFunc():
      #some code
      _flag = 1
      secondFunction()

def fourthFunction():
   #some code
   while [condition]:
      #some code
      #here calling funcInFunc() inside thirdFunction()
      funcInFunc()
      #need to wait for mainFunction() called from secondFunction() called from        funcInFunc() to finish before next iteration of this while loop
      if _flag == 1 
 
      #WAIT FOR mainFunction() TO FINISH
      if _flag == 0

Don't forget to declare it global where useful. When _flag == 1, it can go on. When _flag == 0, it can iterate