How to set timeout for urlfetch in Google App Engine?

user_251393 0
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I'm trying to have Django (on top of GAE) fetch data from another web service. I'm often hit with error like this:

ApplicationError: 2 timed out Request

Method: GET

Request URL:http://localhost:8080/

Exception Type: DownloadError

Exception Value: ApplicationError: 2 timed out

Exception Location: /google_appengine/google/appengine/api/urlfetch.py in _get_fetch_result, line 325

It feels as if it will time out only after 12 seconds (I'm not sure, but it's really short).

Question: how can I set a longer timeout?

timeout google-app-engine django python
4 Answers

You can set it using the deadline argument of the fetch function. From the docs:

The deadline can be up to a maximum of 60 seconds for request handlers and 10 minutes for tasks queue and cron job handlers. If deadline is None, the deadline is set to 5 seconds.

Edit: looks like this has changed now. From here:

You can set a deadline for a request, the most amount of time the service will wait for a response. By default, the deadline for a fetch is 5 seconds. You can adjust the default deadline for requests using the urlfetch.set_default_fetch_deadline() function.

And this page lists the default timeout values:

Currently, there are several errors named DeadlineExceededError for the Python runtime:

  • google.appengine.runtime.DeadlineExceededError: raised if the overall request times out, typically after 60 seconds, or 10 minutes for task queue requests.
  • google.appengine.runtime.apiproxy_errors.DeadlineExceededError: raised if an RPC exceeded its deadline. This is typically 5 seconds, but it is settable for some APIs using the 'deadline' option.
  • google.appengine.api.urlfetch_errors.DeadlineExceededError: raised if the URLFetch times out.
user_431400

It seems short but you have to know that the timeout of a request on GAE is around 30 seconds. As you probably need to do some operations on the response of your urlfetch, there's no need to have a timeout more than 10 seconds I think.

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