I have a cherrypy app that's got a Monitor instance like so:
mail_checker = Monitor(cherrypy.engine, self.mail_processor.poll_history_feed, frequency=10)
To put it simply it checks a gmail inbox for new emails and processes them. Sometimes poll_history_feed() will throw an exception, I'm guessing right now that its because of our unstable internet, and it ceases to run until I restart the whole app. (sample of the traceback below)
[01/Mar/2016:17:08:29] ENGINE Error in background task thread function <bound method MailProcessor.poll_history_feed of <mailservices.mailprocessor.MailProcessor object at 0x10a2f0250>>.
Traceback (most recent call last):
File "/Users/hashtaginteractive/Projects/.venvs/emaild/lib/python2.7/site-packages/cherrypy/process/plugins.py", line 500, in run
self.function(*self.args, **self.kwargs)
File "/Users/hashtaginteractive/Projects/emaild/emaild-source/mailservices/mailprocessor.py", line 12, in poll_history_feed
labelIds=["INBOX", "UNREAD"]
File "/Users/hashtaginteractive/Projects/.venvs/emaild/lib/python2.7/site-packages/oauth2client/util.py", line 142, in positional_wrapper
return wrapped(*args, **kwargs)
File "/Users/hashtaginteractive/Projects/.venvs/emaild/lib/python2.7/site-packages/googleapiclient/http.py", line 730, in execute
return self.postproc(resp, content)
File "/Users/hashtaginteractive/Projects/.venvs/emaild/lib/python2.7/site-packages/googleapiclient/model.py", line 207, in response
return self.deserialize(content)
File "/Users/hashtaginteractive/Projects/.venvs/emaild/lib/python2.7/site-packages/googleapiclient/model.py", line 262, in deserialize
content = content.decode('utf-8')
File "/Users/hashtaginteractive/Projects/.venvs/emaild/lib/python2.7/encodings/utf_8.py", line 16, in decode
return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x8b in position 23: invalid start byte
Is there any way to set this up so that it automatically restarts either the server or this particular Monitor instance whenever an exception happens?
You have to wrap the call to self.mail_processor.poll_history_feed in a try/except block and log the error for convenience.
def safe_poll_history_feed(self):
try:
self.mail_processor.poll_history_feed()
except Exception:
cherrypy.engine.log("Exception in mailprocessor monitor", traceback=True)
And then use the safe_poll_history_feed method