When to call thread.join in a GUI application

When to call thread.join in a GUI application - Printable Version

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When to call thread.join in a GUI application - QueenSvetlana - Nov-14-2017

import wx
import json
import queue
import threading


class MyDialog(wx.Frame):

    def __init__(self, parent, title):
        self.no_resize = wx.DEFAULT_FRAME_STYLE & ~ (wx.RESIZE_BORDER | wx.MAXIMIZE_BOX)
        wx.Frame.__init__(self, parent, title=title, size=(500, 450),style = self.no_resize)

        self.panel = wx.Panel(self, size=(250, 270))
        self.emp_selection = wx.ComboBox(self.panel, -1, pos=(40, 50), size=(200,100))
        self.start_read_thread()

        #code to load other GUI components             

        self.Centre()
        self.Show(True)


    def read_employees(self, read_file):
        list_of_emails = queue.Queue()
        with open(read_file) as f_obj:
            employees = json.load(f_obj)
        list_of_emails = [empEmail for empEmail in employees.keys()]
        wx.CallAfter(self.emp_selection.Append, list_of_emails)

    def start_read_thread(self):
        filename = 'employee.json'
        empThread = threading.Thread(target=self.read_employees, args=(filename,))
        empThread.start()

I have a GUI application that loads a combobox, and starts a thread to read some data and load it into the combobox. I don't want the read to block, so that the other GUI components can load.

After calling thread.start() when is it appropriate to call thread.join()? From my understanding, join() waits for the thread to complete, I don't want that, I want to start the thread and allow all the other components to load. Is it bad practice not to call join()?