Python script stops running after 15-20h

Question

I'm monitoring my sensor data and sending it online with my .py srcipt. It should run every 5min so I programed it like this:

import threading
import time 
def send_wu():
 # Read sensors
 temperature = sensor.read_temperature()
 humidity,t_old = dht.read_retry(dht.DHT22, 4)
 pressure = (sensor.read_pressure()*0.01)+13 # Correct pressure
 # Prevent wrong reading
 while pressure>1030 or pressure<1000:
 pressure=(sensor.read_pressure()*0.01)+13
 def dewpoint_approximation(T,RH):
 Td = (237.7 * gamma(T,RH)) / (17.271 - gamma(T,RH))
 return Td
 def gamma(T,RH):
 g = (17.271 * T / (237.7 + T)) + log(RH/100.0)
 return g
 dewpoint = dewpoint_approximation(temperature,humidity)
 date = "now"
 data = "http://weatherstation.wunderground.com/weatherstation/updateweatherstation.php?ID=IGRADZAGxx&PASSWORD=xxxxxx&dateutc=now&tempf={0:.1f}&baromin={1}&humidity={2}&dewptf={3}&softwaretype=Custom&action=updateraw".format(temperature*1.8+32,pressure*0.0295299830714,humidity,dewpoint*1.8+32)
 response = urllib2.urlopen(data).read()
 print time.strftime("%Y-%m-%d %H:%M:%S")+" Wunderground: "+response
 # Run every 5 min
 threading.Timer(300, send_wu).start()

It works fine for 15-20h but then it stops, here comes the interesting part. When I fire up the putty it restarts the script and runs it again. What's stoping my script from running?

EDIT:

I managed to "catch" the error:

Exception in thread Thread-317:
Traceback (most recent call last):
 File "/usr/lib/python2.7/threading.py", line 552, in __bootstrap_inner
 self.run()
 File "/usr/lib/python2.7/threading.py", line 760, in run
 self.function(*self.args, **self.kwargs)
 File "meteo_stanica.py", line 181, in posalji_wu
 response = urllib2.urlopen(data).read()
 File "/usr/lib/python2.7/urllib2.py", line 127, in urlopen
 return _opener.open(url, data, timeout)
 File "/usr/lib/python2.7/urllib2.py", line 401, in open
 response = self._open(req, data)
 File "/usr/lib/python2.7/urllib2.py", line 419, in _open
 '_open', req)
 File "/usr/lib/python2.7/urllib2.py", line 379, in _call_chain
 result = func(*args)
 File "/usr/lib/python2.7/urllib2.py", line 1211, in http_open
 return self.do_open(httplib.HTTPConnection, req)
 File "/usr/lib/python2.7/urllib2.py", line 1184, in do_open
 r = h.getresponse(buffering=True)
 File "/usr/lib/python2.7/httplib.py", line 1034, in getresponse
 response.begin()
 File "/usr/lib/python2.7/httplib.py", line 407, in begin
 version, status, reason = self._read_status()
 File "/usr/lib/python2.7/httplib.py", line 365, in _read_status
 line = self.fp.readline()
 File "/usr/lib/python2.7/socket.py", line 447, in readline
 data = self._sock.recv(self._rbufsize)
error: [Errno 110] Connection timed out

So the problem is timed out connection, I added "timeout", in 15-20h we'll see if that helps.

response = urllib2.urlopen(data, timeout=20).read()

• Boštjan Jerko: Do you get any info when it stops?
• Pas: No, on wunderground weather station page just says that PWS is not reporting.
• joan: Could you post a complete runnable example? it can still be brief, but the given snippet is not enough context.
• Pas: @joan I edited the question
• ifermon: I'd bet that you have network issues. Try installing watchdog and setting it up to ping your local gateway, or you can just have a script that runs ping (e.g. ping -D -i 300 local.gateway.ip.goes.here). Log the output of the script to a file. See if it fails around the same time you have the issues.

Answer 1

Network connections will fail once in a while. Best thing to do is handle the failure. The following will handle socket errors. At the top of your file, import socket:

import socket

Then, update your code:

response = urllib2.urlopen(data).read()

with the following:

try:
 response = urllib2.urlopen(data).read()
except socket.error, exc:
 print 'socket error {}, skipping data={}'.format(exc[0], data)

As written above, you'll lose this temperature reading, but the script will keep going. You can make it try to post more than once if you want:

for i in range(3): # try three times
 try:
 response = urllib2.urlopen(data).read()
 except socket.error, exc:
 print 'socket error {}...'.format(exc[0])
 else:
 break # success, don't retry
else:
 print 'cannot post, skipping data={}'.format(data)