Tasks will fail when settings.USE_TZ = False

[ryanbagwell]

By default, the Django setting USE_TZ = False. This will throw errors when running tasks because this reference to the current time is not timezone aware.

The tests pass because they're bypassing the task running command.

I'm not sure what the best way to handle this is. My thought is that we should require USE_TZ to be True for consistency, and if it's not, throw an assertion error with a clear explanatory message.

I created an additional test in order to test the runner task. It's in a branch tz-issues.

[matthewwithanm]

According to this SO question, timezone.now() is supposed to respect USE_TZ and return a timezone-aware datetime. Is the problem that it's always UTC?

[ryanbagwell]

From the Django docs for timezone.now():

If USE_TZ is False, this will be a naive datetime (i.e. a datetime without an associated timezone) that represents the current time in the system’s local timezone.

If USE_TZ is True, this will be an aware datetime representing the current time in UTC. Note that now() will always return times in UTC regardless of the value of TIME_ZONE; you can use localtime() to convert to a time in the current time zone.

By default, USE_TZ = False, which means by default, timezone.now() will not return an aware datetime.

[matthewwithanm]

Oh, so the issue is that a time generated elsewhere is timezone aware, mucking up the comparison?

[ryanbagwell]

Exactly. Here's the first culprit.

[matthewwithanm]

Where's the date that one's being compared to? Also, can you paste a stacktrace?

[ryanbagwell]

The schedule class is where the comparison object is made timezone aware.

The comparison is happening in the time_before method of the schedule class.

The time_before() method gets called in utils.get_scheduled_time() which passes the unaware datetime object.

utils.get_scheduled_time() is called by backends.BaseBackend._run_tasks(), which is where the unaware datetime is created.

[matthewwithanm]

Ah, so maybe we should only make this guy timezone aware if settings.USE_TZ?