如何在Flask应用程序中启动后台线程?

Question

我写了一个运行良好的Flask应用程序，我希望当它运行时，一个单独的后台线程应该并行于它做一些事情。问题是，这样做根本不会产生线程，但我知道我的代码是正确的，因为在一个简单的python脚本上使用线程代码的完全相同的部分按预期工作。

app.py

weatherCollectorThread = WeatherDataCollectorThread()
...
if __name__ == '__main__':
try:
print("Starting Weather Collector Thread...")       
weatherCollectorThread.start()
print("Starting the WebApp...")
app.run(debug=True)
except KeyboardInterrupt:
try:
weatherCollectorThread.stop()
except:
pass

<<p>WeatherDataCollectorThread类/strong>

class WeatherDataCollectorThread:
def __init__(self):
self.weatherStations = DBHelper.get_weather_stations()
self.weatherApiKey = "REDACTED"
self.baseURL = "SOME URL"
self.isThreadRunning = False
self.result_log = open('results.log','a+')
def storeWeatherData(self,weather):
conn = DBHelper.get_connection()
cur = conn.cursor()
cur.execute("INSERT INTO weather_data(city,country,now_unixtime,last_updated_unixtime,temperature,isDay,condition_text,condition_icon,windspeed,winddir,pressure,precipitation,cloud,humidity) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?)",[weather['city'],weather['country'],weather['now_unixtime'],weather['last_updated_unixtime'],weather['temperature'],weather['isDay'],weather['condition_text'],weather['condition_icon'],weather['windspeed'],weather['winddir'],weather['pressure'],weather['precipitation'],weather['cloud'],weather['humidity']])
conn.commit()
conn.close()
def collectWeatherData(self):
self.isThreadRunning = True 
while self.isThreadRunning: 
for each_station in self.weatherStations:
if each_station['isWorking'] != 1:
continue
print("Sending request")
params = {'q':each_station['location'],'key':self.weatherApiKey}
resp = requests.get(url=self.baseURL,params=params)
print("Request received")
weatherData = json.loads(resp.text)
location = weatherData['location']
current = weatherData['current']
weather = {}
weather['city'] = location['name']
weather['country'] = location['country']
weather['now_unixtime'] = location['localtime_epoch']
weather['last_updated_unixtime'] = current['last_updated_epoch']
weather['temperature'] = current['temp_c']
weather['isDay'] = current['is_day']
weather['condition_text'] = current['condition']['text']
weather['condition_icon'] = current['condition']['icon']
weather['windspeed'] = current['wind_kph']
weather['winddir'] = current['wind_dir']
weather['pressure'] = current['pressure_mb']
weather['precipitation'] = current['precip_mm']
weather['cloud'] = current['cloud']
weather['humidity'] = current['humidity']
self.storeWeatherData(weather)
print("Data storedn" + '-'*24)
self.result_log.write(resp.text + 'n')

sleep(60)
def start(self):
self.thread = Thread(target=self.collectWeatherData)
self.thread.start()
def join_instrument(self,session):
conn = DBHelper.get_connection()
cur = conn.cursor()
cur.execute("UPDATE weather_stations SET isWorking=1 WHERE weatherStationID=?",[session['weatherStationID']])
conn.commit()
conn.close()
def detach_instrument(self,session):
conn = DBHelper.get_connection()
cur = conn.cursor()
cur.execute("UPDATE weather_stations SET isWorking=0 WHERE weatherStationID=?",[session['weatherStationID']])
conn.commit()
conn.close()
def stop(self):
self.result_log.close()
self.isThreadRunning = False

Answer 1

于是我想出了解决办法。

你看，当你使用flask run来运行你的web应用程序时，它会忽略脚本中的每个函数调用，并通过装饰器进行解析，然后自己启动应用程序。所以，如果你这样做:

if __name__ == '__main__':
app.start()
someOtherFunction()

app.start()和someOtherFunction()都不启动

那么解决方案是什么呢?

直接使用python3 app.py运行脚本

…是的，就是这么简单:|