Troubleshooting and Common Pitfalls

This document outlines some of the common pitfalls you may encounter when getting set up with huey. It is arranged in a problem/solution format.

Tasks not running

First step is to increase logging verbosity by running the consumer with --verbose. You can also specify a logfile using the --logfile option.

Check for any exceptions. The most common cause of tasks not running is that they are not being loaded, in which case you will see HueyException “XXX not found in TaskRegistry” errors.

“HueyException: XXX not found in TaskRegistry” in log file

Exception occurs when a task is called by a task producer, but is not imported by the consumer. To fix this, ensure that by loading the Huey object, you also import any decorated functions as well.

For more information on how tasks are imported, see the import documentation.

“Error importing XXX” when starting consumer

This error message occurs when the module containing the configuration specified cannot be loaded (not on the pythonpath, mistyped, etc). One quick way to check is to open up a python shell and try to import the configuration.

Example syntax: main_module.huey

Tasks not returning results

Ensure that you have not accidentally specified results=False when instantiating your Huey object.

Additionally note that, by default, Huey does not store None in the result-store. So if your task returns None, Huey will discard the result. If you need to block or detect whether a task has finished, it is recommended that you return a non-None value or in extreme circumstances you can initialize Huey with store_none=True (though this can quickly fill up your result store and is only recommended for users who are very familiar with Huey).

Scheduled tasks are not being run at the correct time

Check the time on the server the consumer is running on - if different from the producer this may cause problems. Huey uses UTC internally by default, and naive datetimes will be converted from local time to UTC (if local time happens to not be UTC).

Cronjobs are not being run

The consumer and scheduler run in UTC by default.

Greenlet workers seem stuck

If you wish to use the Greenlet worker type, you need to be sure to monkeypatch in your application’s entrypoint. At the top of your main module, you can add the following code: from gevent import monkey; monkey.patch_all(). Furthermore, if your tasks are CPU-bound, gevent can appear to lock up because it only supports cooperative multi-tasking (as opposed to pre-emptive multi-tasking when using threads). For Django, it is necessary to apply the patch inside the script. See the Django docs section for the code.

Testing projects using Huey

Use immediate=True:

test_mode = os.environ.get('TEST_MODE')

# When immediate=True, Huey will default to using an in-memory
# storage layer.
huey = RedisHuey(immediate=test_mode)

# Alternatively, you can set the `immediate` attribute:
huey.immediate = True if test_mode else False