Python 3.x Python websockets和gtk-对异步IO队列感到困惑
我是python异步编程新手,我正在尝试编写一个脚本,该脚本启动websocket服务器,侦听消息,并在gtk窗口中触发某些事件(例如按下“s”键)时发送消息。以下是我目前掌握的情况:Python 3.x Python websockets和gtk-对异步IO队列感到困惑,python-3.x,websocket,gtk3,python-asyncio,Python 3.x,Websocket,Gtk3,Python Asyncio,我是python异步编程新手,我正在尝试编写一个脚本,该脚本启动websocket服务器,侦听消息,并在gtk窗口中触发某些事件(例如按下“s”键)时发送消息。以下是我目前掌握的情况: import gi gi.require_version('Gtk', '3.0') from gi.repository import Gtk import asyncio import websockets import threading ws = None async def consumer_han
import gi
gi.require_version('Gtk', '3.0')
from gi.repository import Gtk
import asyncio
import websockets
import threading
ws = None
async def consumer_handler(websocket, path):
global ws
ws = websocket
await websocket.send("Hello client")
while True:
message = await websocket.recv()
print("Message from client: " + message)
def keypress(widget,event):
global ws
if event.keyval == 115 and ws: #s key pressed, connection open
asyncio.get_event_loop().create_task(ws.send("key press"))
print("Message to client: key press")
def quit(widget):
Gtk.main_quit()
window = Gtk.Window(Gtk.WindowType.TOPLEVEL)
window.connect("destroy", quit)
window.connect("key_press_event", keypress)
window.show()
start_server = websockets.serve(consumer_handler, 'localhost', 8765)
asyncio.get_event_loop().run_until_complete(start_server)
wst = threading.Thread(target=asyncio.get_event_loop().run_forever)
wst.daemon = True
wst.start()
Gtk.main()
以下是客户端网页:
<!DOCTYPE html>
<html>
<head>
<title>Websockets test page</title>
<meta charset="UTF-8" />
<script>
var exampleSocket = new WebSocket("ws://localhost:8765");
function mylog(msg) {
document.getElementById("log").innerHTML += msg + "<br/>";
}
function send() {
mylog("Message to server: Hello server");
exampleSocket.send("Hello server");
}
exampleSocket.onopen = function (event) {
mylog("Connection opened");
};
exampleSocket.onmessage = function (event) {
mylog("Message from server: " + event.data);
}
</script>
</head>
<body>
<p id="log"></p>
<input type="button" value="Send message" onclick="send()"/>
</body>
</html>
WebSocket测试页
var exampleSocket=newWebSocket(“ws://localhost:8765”);
函数mylog(msg){
document.getElementById(“log”).innerHTML+=msg+“
”;
}
函数send(){
mylog(“发送给服务器的消息:Hello server”);
示例socket.send(“Hello服务器”);
}
exampleSocket.onopen=函数(事件){
mylog(“连接已打开”);
};
exampleSocket.onmessage=函数(事件){
mylog(“来自服务器的消息:+event.data”);
}
运行python代码,然后在浏览器中加载网页,现在浏览器发送的任何消息都会显示在python标准输出中,到目前为止效果良好。但是,如果您在gtk窗口中点击“s”键,python将不会发送消息,直到从浏览器接收到另一条消息(通过按下“发送消息”按钮)。我以为等待websocket.recv()
是为了在收到消息之前将控制权返回到事件循环?如何让它在等待接收时发送消息
但是,如果在gtk窗口中点击“s”键,python将在收到来自浏览器的另一条消息之前不发送该消息
问题出在这一行:
asyncio.get_event_loop().create_task(ws.send("key press"))
由于asyncio事件循环和GTK主循环在不同的线程中运行,因此需要使用将协程提交给asyncio。比如:
asyncio.run_coroutine_threadsafe(ws.send("key press"), loop)
create\u task
将协同路由添加到可运行的协同路由队列中,但无法唤醒事件循环,这就是为什么只有在异步IO中发生其他事件时才运行协同路由。另外,create_task
不是线程安全的,因此在事件循环本身修改运行队列时调用它可能会损坏其数据结构run\u coroutine\u threadsafe
没有这两个问题,它安排事件循环尽快唤醒,并使用互斥来保护事件循环的数据结构