1. 目的
曾經想向前臺實時返回Celery任務的狀態監控,也查看了很多博客,但是好多也沒能如願,因此基於網上已有的博客已經自己的嘗試,寫了一個小的demo,實現前臺實時獲取後臺傳輸的任務狀態。
2. 準備
本篇文章使用的是Flask框架,安裝celery,celery採用redis作爲存儲。同時用到了Flask-SocketIO建立websocket。同時還用到了協程庫eventlet(這個是Flask-SocketIO文檔建議的,鏈接文檔)。
3. 實現
demo仿照其他例子實現了一個簡單的後臺任務監控。我們直接上代碼吧,下面是server端代碼:
# -*- utf-8 -*-
# app.py
import time
import uuid
from flask import Flask, render_template, request, make_response, jsonify
from flask_socketio import SocketIO
from celery import Celery
import eventlet
from flask_redis import FlaskRedis
eventlet.monkey_patch()
app = Flask(__name__)
app.config['BROKER_URL'] = 'redis://localhost:6379/0'
app.config['CELERY_RESULT_BACKEND'] = 'redis://localhost:6379/0'
app.config['CELERY_ACCEPT_CONTENT'] = ['json', 'pickle']
app.config['REDIS_URL'] = 'redis://localhost:6379/0'
socketio = SocketIO(app, async_mode='eventlet',message_queue=app.config['CELERY_RESULT_BACKEND'])
redis = FlaskRedis(app)
celery = Celery(app.name)
celery.conf.update(app.config)
#模擬後臺耗時任務
@celery.task
def background_task(uid):
sid = redis.get(uid)
socketio.emit('info', {'data': 'Task starting ...', 'time': time.time() * 1000 },room=sid, namespace='/task')
socketio.sleep(4)
socketio.emit('info', {'data': 'Task running!', 'time': time.time() * 1000 }, room=sid, namespace='/task')
socketio.sleep(5)
socketio.emit('info', {'data': 'Task complete!', 'time': time.time()*1000 }, room=sid, namespace='/task')
#建立鏈接時把sid傳到瀏覽器端保存。
@socketio.on('connect', namespace='/task')
def connect_host():
sid = request.sid
socketio.emit('hostadd', {'sid': sid}, room=sid, namespace='/task')
#將每一個客戶端生成一個uuid存放在cookie中
@app.route('/')
def index():
if not request.cookies.get('host_uid', None):
uid = uuid.uuid1().get_hex()
response = make_response(render_template('index.html'))
response.set_cookie('host_uid', uid)
return response
return render_template('index.html')
@app.route('/task')
def start_background_task():
uid = request.cookies.get('host_uid')
background_task.delay(uid)
return 'Started'
#設置sid建立鏈接後瀏覽器將sid傳送到server,並將uid與sid映射存放在redis裏面,默認保留12小時
@app.route('/setsid', methods=['POST'])
def set_uid():
data = request.json
uid = request.cookies.get('host_uid')
redis.set(uid, data['sid'])
redis.expire(uid, 3600 * 12)
return jsonify({'success': True})
if __name__ == '__main__':
socketio.run(app, host='0.0.0.0', port=5000, debug=True)
如果不想使用debug模式的話,可以用gunicorn運行,命令如下所示:
gunicorn --worker-class eventlet -w 1 app:app
使用上述命令需要注意,由於gunicorn負載均衡算法的限制,文檔建議worker數量爲1,我測試過大於1,確實會出問題。
前端代碼如下,index.html:
<!DOCTYPE html>
<html>
<head>
<title>test</title>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/2.1.0/socket.io.js"></script>
</head>
<body>
<h3>Logging</h3>
<p id="log"></p>
<button id="background">Execute</button>
<script type="text/javascript">
$(document).ready(function () {
namespace = '/task';
socket = io.connect('http://' + document.domain + ':' + location.port + namespace);
socket.on('hostadd', function(msg){
console.log(msg.sid);
$.ajax({
url: "{{ url_for('set_uid') }}",
data: JSON.stringify({ sid: msg.sid }),
type: 'post',
dataType: 'json',
contentType: "application/json; charset=utf-8"
})
});
socket.on('info', function (msg) {
console.log('Recived: ' + msg.data);
var t = new Date(msg.time);
$('#log').append('Recived: ' + t.toLocaleTimeString() + '->' + msg.data + '<br>');
});
$('#background').on('click', function(){
$.get("{{ url_for('start_background_task') }}");
});
});
</script>
</body>
</html>
GitHub地址:https://github.com/junfenggoo...