我想将asyncio与tkinter GUI结合使用。我是asyncio的新手，我对它的理解不是很详细。单击第一个按钮时，此示例启动10个任务。任务只是使用sleep()模拟工作几秒钟。
使用Python 3.6.4rc1可以正常运行示例代码。但问题是GUI被冻结了。当我按下第一个按钮并启动10个asyncio任务时，我无法按下GUI中的第二个按钮，直到完成所有任务。 GUI永远不应该冻结 - 这是我的目标。
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from tkinter import *
from tkinter import messagebox
import asyncio
import random
def do_freezed():
""" Button-Event-Handler to see if a button on GUI works. """
messagebox.showinfo(message='Tkinter is reacting.')
def do_tasks():
""" Button-Event-Handler starting the asyncio part. """
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(do_urls())
finally:
loop.close()
async def one_url(url):
""" One task. """
sec = random.randint(1, 15)
await asyncio.sleep(sec)
return 'url: {}\tsec: {}'.format(url, sec)
async def do_urls():
""" Creating and starting 10 tasks. """
tasks = [
one_url(url)
for url in range(10)
]
completed, pending = await asyncio.wait(tasks)
results = [task.result() for task in completed]
print('\n'.join(results))
if __name__ == '__main__':
root = Tk()
buttonT = Button(master=root, text='Asyncio Tasks', command=do_tasks)
buttonT.pack()
buttonX = Button(master=root, text='Freezed???', command=do_freezed)
buttonX.pack()
root.mainloop()
...是因为这个错误我无法再次运行任务。
Exception in Tkinter callback
Traceback (most recent call last):
File "/usr/lib/python3.6/tkinter/__init__.py", line 1699, in __call__
return self.func(*args)
File "./tk_simple.py", line 17, in do_tasks
loop.run_until_complete(do_urls())
File "/usr/lib/python3.6/asyncio/base_events.py", line 443, in run_until_complete
self._check_closed()
File "/usr/lib/python3.6/asyncio/base_events.py", line 357, in _check_closed
raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
多线程是一种可能的解决方案吗？只有两个线程 - 每个循环都有它自己的线程？
编辑：在回顾这个问题和答案后，它几乎与所有GUI库（例如PygObject / Gtk，wxWidgets，Qt，...）相关。
稍微修改了一下代码，我在主线程中创建了asyncio event_loop，并将其作为参数传递给asyncio线程。现在Tkinter在获取网址时不会冻结。
from tkinter import *
from tkinter import messagebox
import asyncio
import threading
import random
def _asyncio_thread(async_loop):
async_loop.run_until_complete(do_urls())
def do_tasks(async_loop):
""" Button-Event-Handler starting the asyncio part. """
threading.Thread(target=_asyncio_thread, args=(async_loop,)).start()
async def one_url(url):
""" One task. """
sec = random.randint(1, 8)
await asyncio.sleep(sec)
return 'url: {}\tsec: {}'.format(url, sec)
async def do_urls():
""" Creating and starting 10 tasks. """
tasks = [one_url(url) for url in range(10)]
completed, pending = await asyncio.wait(tasks)
results = [task.result() for task in completed]
print('\n'.join(results))
def do_freezed():
messagebox.showinfo(message='Tkinter is reacting.')
def main(async_loop):
root = Tk()
Button(master=root, text='Asyncio Tasks', command= lambda:do_tasks(async_loop)).pack()
buttonX = Button(master=root, text='Freezed???', command=do_freezed).pack()
root.mainloop()
if __name__ == '__main__':
async_loop = asyncio.get_event_loop()
main(async_loop)
试图同时运行两个事件循环是一个可疑的命题。但是，由于root.mainloop只是重复调用root.update，因此可以通过重复调用update作为asyncio任务来模拟mainloop。这是一个测试程序。我认为向tkinter任务添加asyncio任务会起作用。我检查它仍然以3.7.0a2运行。
"""Proof of concept: integrate tkinter, asyncio and async iterator.
Terry Jan Reedy, 2016 July 25
"""
import asyncio
from random import randrange as rr
import tkinter as tk
class App(tk.Tk):
def __init__(self, loop, interval=1/120):
super().__init__()
self.loop = loop
self.protocol("WM_DELETE_WINDOW", self.close)
self.tasks = []
self.tasks.append(loop.create_task(self.rotator(1/60, 2)))
self.tasks.append(loop.create_task(self.updater(interval)))
async def rotator(self, interval, d_per_tick):
canvas = tk.Canvas(self, height=600, width=600)
canvas.pack()
deg = 0
color = 'black'
arc = canvas.create_arc(100, 100, 500, 500, style=tk.CHORD,
start=0, extent=deg, fill=color)
while await asyncio.sleep(interval, True):
deg, color = deg_color(deg, d_per_tick, color)
canvas.itemconfigure(arc, extent=deg, fill=color)
async def updater(self, interval):
while True:
self.update()
await asyncio.sleep(interval)
def close(self):
for task in self.tasks:
task.cancel()
self.loop.stop()
self.destroy()
def deg_color(deg, d_per_tick, color):
deg += d_per_tick
if 360 <= deg:
deg %= 360
color = '#%02x%02x%02x' % (rr(0, 256), rr(0, 256), rr(0, 256))
return deg, color
loop = asyncio.get_event_loop()
app = App(loop)
loop.run_forever()
loop.close()
随着间隔减小，tk更新开销和时间分辨率都增加。对于gui更新，与动画相反，每秒20个就足够了。
我最近成功运行了包含tkinter调用的异步def协程，并等待了mainloop。原型使用asyncio Tasks和Futures，但我不知道添加正常的asyncio任务是否有效。如果想要一起运行asyncio和tkinter任务，我认为使用asyncio循环运行tk update是一个更好的主意。
编辑：至少如上所述，没有异步def协同程序的异常会杀死协程，但会被捕获并丢弃。沉默的错误非常令人讨厌。
通过在正确的位置添加对Button的调用，按下root.update_idletasks()后，可以保持GUI处于活动状态：
from tkinter import *
from tkinter import messagebox
import asyncio
import random
def do_freezed():
""" Button-Event-Handler to see if a button on GUI works. """
messagebox.showinfo(message='Tkinter is reacting.')
def do_tasks():
""" Button-Event-Handler starting the asyncio part. """
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(do_urls())
finally:
loop.close()
async def one_url(url):
""" One task. """
sec = random.randint(1, 15)
root.update_idletasks() # ADDED: Allow tkinter to update gui.
await asyncio.sleep(sec)
return 'url: {}\tsec: {}'.format(url, sec)
async def do_urls():
""" Creating and starting 10 tasks. """
tasks = [one_url(url) for url in range(10)]
completed, pending = await asyncio.wait(tasks)
results = [task.result() for task in completed]
print('\n'.join(results))
if __name__ == '__main__':
root = Tk()
buttonT = Button(master=root, text='Asyncio Tasks', command=do_tasks)
buttonT.pack()
buttonX = Button(master=root, text='Freezed???', command=do_freezed)
buttonX.pack()
root.mainloop()
我很幸运在另一个线程上运行I / O循环，在应用程序创建开始时启动，并使用asyncio.run_coroutine_threadsafe(..)将任务抛到其上。
我很惊讶我可以在另一个asyncio循环/线程上更改tkinter小部件，也许这对我来说是一个侥幸 - 但它确实有效。
请注意，当asyncio任务正在发生时，另一个按钮仍处于活动状态且正在响应。我总是喜欢另一个按钮上的禁用/启用功能，所以你不会意外触发多个任务，但这只是一个UI的事情。
import threading
from functools import partial
from tkinter import *
from tkinter import messagebox
import asyncio
import random
# Please wrap all this code in a nice App class, of course
def _run_aio_loop(loop):
asyncio.set_event_loop(loop)
loop.run_forever()
aioloop = asyncio.new_event_loop()
t = threading.Thread(target=partial(_run_aio_loop, aioloop))
t.daemon = True # Optional depending on how you plan to shutdown the app
t.start()
buttonT = None
def do_freezed():
""" Button-Event-Handler to see if a button on GUI works. """
messagebox.showinfo(message='Tkinter is reacting.')
def do_tasks():
""" Button-Event-Handler starting the asyncio part. """
buttonT.configure(state=DISABLED)
asyncio.run_coroutine_threadsafe(do_urls(), aioloop)
async def one_url(url):
""" One task. """
sec = random.randint(1, 3)
# root.update_idletasks() # We can delete this now
await asyncio.sleep(sec)
return 'url: {}\tsec: {}'.format(url, sec)
async def do_urls():
""" Creating and starting 10 tasks. """
tasks = [one_url(url) for url in range(3)]
completed, pending = await asyncio.wait(tasks)
results = [task.result() for task in completed]
print('\n'.join(results))
buttonT.configure(state=NORMAL) # Tk doesn't seem to care that this is called on another thread
if __name__ == '__main__':
root = Tk()
buttonT = Button(master=root, text='Asyncio Tasks', command=do_tasks)
buttonT.pack()
buttonX = Button(master=root, text='Freezed???', command=do_freezed)
buttonX.pack()
root.mainloop()