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Tkinter background threading example
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#!/usr/bin/env python3 | |
# encoding=utf-8 | |
# vim: set nobomb: | |
from tkinter import * | |
from threading import Thread, Lock, Event | |
from queue import SimpleQueue | |
from time import sleep | |
from typing import List | |
import random | |
class WorkerThread(Thread): | |
def __init__(self, interface: 'HMI', callback, idx: int): | |
super().__init__() | |
self.interface = interface | |
self.callback = callback | |
self.idx = idx | |
def run(self): | |
count = 0 | |
while not self.interface.exit_event.is_set(): | |
count += 1 | |
self.callback(self.idx, count) | |
sleep(random.random() / 1000) | |
class HMI: | |
def __init__(self): | |
self._exit_event = Event() | |
self._event_locks = [Lock() for i in range(2)] | |
self.master = Tk() | |
self.master.geometry('200x200+1+1') | |
f = Frame(self.master) | |
f.pack() | |
self.l0 = Label(f) | |
self.l0.pack() | |
self.l1 = Label(f) | |
self.l1.pack() | |
self.q0 = SimpleQueue() | |
self.q1 = SimpleQueue() | |
self.master.bind("<<Thread_0_Label_Update>>", self.thread_0_update_e) | |
self.master.bind("<<Thread_1_Label_Update>>", self.thread_1_update_e) | |
self.master.protocol("WM_DELETE_WINDOW", self.closing) | |
@property | |
def exit_event(self) -> Event: | |
return self._exit_event | |
@property | |
def event_locks(self) -> List[Lock]: | |
return self._event_locks | |
def start(self): | |
self.master.mainloop() | |
# now that we've shut down, and the workers aren't going to send more messages, this is safe. | |
for lock in self.event_locks: | |
lock.release() | |
def closing(self): | |
# set this event to tell the workers to exit | |
self.exit_event.set() | |
# acquire these locks so we know the workers aren't sending more messages | |
for lock in self.event_locks: | |
while not lock.acquire(False): | |
# someone is waiting on us to pump messages while they hold the lock | |
self.master.update() | |
# now that we have the locks, it's safe to start shutting down | |
self.master.destroy() | |
################################# | |
def thread_0_update(self, idx, val): | |
self.q0.put_nowait(val) | |
with self.event_locks[idx]: | |
if not self.exit_event.is_set(): | |
self.master.event_generate('<<Thread_0_Label_Update>>', when='tail') | |
def thread_1_update(self, idx, val): | |
self.q1.put_nowait(val) | |
with self.event_locks[idx]: | |
if not self.exit_event.is_set(): | |
self.master.event_generate('<<Thread_1_Label_Update>>', when='tail') | |
def thread_0_update_e(self, e): | |
while not self.q0.empty(): | |
try: | |
val = self.q0.get(False) | |
self.l0.config(text=str(val)) | |
except queue.Empty: | |
pass | |
def thread_1_update_e(self, e): | |
while not self.q1.empty(): | |
try: | |
val = self.q1.get(False) | |
self.l1.config(text=str(val)) | |
except queue.Empty: | |
pass | |
########################## | |
def main(): | |
hmi = HMI() | |
t0 = WorkerThread(hmi, hmi.thread_0_update, 0) | |
t1 = WorkerThread(hmi, hmi.thread_1_update, 1) | |
t0.start() | |
t1.start() | |
hmi.start() | |
if __name__ == "__main__": | |
main() |
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