Python：时间段后停止循环

Question

I am having problems where every now and them my python script will cease to run and i'll stop getting data points added to the db, i want to make the script only run for 10 mins and every 10 mins a cron job will start a new instance.

My code below fails to stop after 10 mins, my python experience is measured in minutes so i'm sure its something obvious to a seasoned Python coder, thanks in advance.

#! /usr/bin/env python

import json
import paho.mqtt.client as mqtt
import requests
import sys
import time

max_time = 600 # 10 mins
start_time = time.time()

def on_connect(client, userdata, flags, rc):
  client.subscribe("zigbee2mqtt/0x0015bc001b238abc")

def on_message(client, userdata, msg):
  requests.post("http://www.url.uk/rpc", data = msg.payload.decode())
  if (time.time() - start_time) < max_time:
    client.loop_stop()
    
client = mqtt.Client()
client.connect("localhost",1883,60)

client.on_connect = on_connect
client.on_message = on_message

client.loop_forever()

Answer 1

From a github issue of the library you are using:

if you need to quit the program after a certain period of not receiving any messages, you might try something like this:

from paho.mqtt.client import Client
import time
client = Client()
client.connect(broker, port)
client.loop_start()
run = True
TIMEOUT = 10  # seconds
while run:
    client._msgtime_mutex.acquire()
    last_msg_in = client._last_msg_in
    client._msgtime_mutex.release()
    now = time.monotonic()
    if now - last_msg_in > TIMEOUT:
        client.disconnect()
        client.loop_stop()
        run = False
    else:
        time.sleep(1)

In your case, the timer can be set to 10*60 seconds and you can avoid using the loop_forever() function.

Answer 2

This is how i achieved it in the end:

#! /usr/bin/env python

import json
import paho.mqtt.client as mqtt
import requests
import sys
import time

max_time = 600 # 10 mins
start_time = time.time()  # remember when we started

def on_connect(client, userdata, flags, rc):
  client.subscribe("zigbee2mqtt/0x0015bc001b238abc")

def on_message(client, userdata, msg):
  if (time.time() - start_time) > max_time:
    client.loop_stop()
    client.disconnect()
    print("Script Ended: Ran For " + str(time.time() - start_time) + " seconds, limit was " + str(max_time))
  else:
    requests.post("http://www.url.uk/rpc", data = msg.payload.decode())
    
client = mqtt.Client()
client.connect("localhost",1883,60)

client.on_connect = on_connect
client.on_message = on_message

client.loop_forever()