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我的程序從傳感器收集數據並將此數據發送到Web界面，該界面以實時圖形顯示併發回一些命令。如何通過使用python燒瓶socket.io和線程異步獲取來自redis的實時數據？
問題是數據發送有很大的延遲或發送舊數據。我應該改變發送數據異步到兩種方式？
我簡化了我的代碼。例1，當數據來自在幾分鐘內一次：
# System stuff
import os
import sys
import serial
# Multiprocessing
from multiprocessing import Process
from threading import Thread # for same memory
import timeit
from time import sleep
# database
import redis
# Web server
from flask import Flask, render_template
from flask_socketio import SocketIO, emit, send, join_room, leave_room, close_room, rooms, disconnect
# Config
DEBUG = True
db = redis.StrictRedis(host='localhost', port=6379, db=0)
#db vars
db.set('velocity', 0.0)
db.set('distance', 0.0)
def webServer(db):
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app)
@app.route('/')
def index():
return render_template('index.html')
def exchangeData():
prev_distance = 0.00
while(True):
distance = round(float(db.get('distance')), 2)
if(distance != prev_distance):
velocity = round(float(db.get('velocity')), 2)
distance = round(float(db.get('distance')), 2)
socketio.emit('exchangeData', {
'velocity': velocity,
'distance': distance,
})
prev_distance = distance
print("DATA sended: %s m/s" % velocity)
sleep(0.2)
@socketio.on('connect')
def test_connect():
t_exchangeData = Thread(target=exchangeData).start()
socketio.run(app, debug=True, host="0.0.0.0")
def newData(db):
c = 0.00
while(True):
db.set('velocity', c)
db.set('distance', c)
c += 1.00
sleep(1)
if __name__ == '__main__':
p_newData = Process(target=newData, args=(db,)).start()
p_webServer = Process(target=webServer, args=(db,)).start()
#p_checkConnection = Process(target=checkConnection, args=(db, HOSTNAME, pinglog)).start()
#p_calcVD = Process(target=calcVD, args=(db,)).start()
在瀏覽器中，我得到這個與潛伏期約2分鐘：
Object {velocity: 218, distance: 218}
// two minutes later
Object {velocity: 306, distance: 306}
// two minutes later
Object {velocity: 306, distance: 306}
例2，當我不if語句和使用睡眠：
# System stuff
import os
import sys
import serial
# Multiprocessing
from multiprocessing import Process
from threading import Thread # for same memory
import timeit
from time import sleep
# database
import redis
# Web server
from flask import Flask, render_template
from flask_socketio import SocketIO, emit, send, join_room, leave_room, close_room, rooms, disconnect
# Config
DEBUG = True
db = redis.StrictRedis(host='localhost', port=6379, db=0)
#db vars
db.set('velocity', 0.0)
db.set('distance', 0.0)
def webServer(db):
app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
socketio = SocketIO(app)
@app.route('/')
def index():
return render_template('index.html')
def exchangeData():
prev_distance = 0.00
while(True):
#distance = round(float(db.get('distance')), 2)
#if(distance != prev_distance):
velocity = round(float(db.get('velocity')), 2)
distance = round(float(db.get('distance')), 2)
socketio.emit('exchangeData', {
'velocity': velocity,
'distance': distance,
})
prev_distance = distance
print("DATA sended: %s m/s" % velocity)
#sleep(0.2)
@socketio.on('connect')
def test_connect():
t_exchangeData = Thread(target=exchangeData).start()
socketio.run(app, debug=True, host="0.0.0.0")
def newData(db):
c = 0.00
while(True):
db.set('velocity', c)
db.set('distance', c)
c += 1.00
sleep(1)
if __name__ == '__main__':
p_newData = Process(target=newData, args=(db,)).start()
p_webServer = Process(target=webServer, args=(db,)).start()
#p_checkConnection = Process(target=checkConnection, args=(db, HOSTNAME, pinglog)).start()
#p_calcVD = Process(target=calcVD, args=(db,)).start()
在這種情況下，我得到的實時數據，但它是相同的數據，並改變只有一次在幾分鐘內：
Object {distance: 3, velocity: 3}
Object {distance: 3, velocity: 3}
Object {distance: 3, velocity: 3}
// repeating around 2 minutes
Object {distance: 357, velocity: 357}
// repeating again...