CODEWITHSUNDEEP
pythondjango
maldahleh
maldahleh

Reputation: 313

Run code on first Django start

I have a Django application written to handle displaying a webpage with data from a model based on the primary key passed in the URL, this all works fine and the Django component is working perfectly for the most part.

My question though is, and I have tried multiple methods such as using an AppConfig, is how I can make it so when the Django server boots up, code is called that would then create a separate thread which would then monitor an external source, logging valid data from that source as a model into the database.

I have the threading code written along with the section that creates the model and saves it in the database, my issue though is that if I try to use an AppConfig to create the thread which would then handle the code, I get an django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet. error and the server does not boot up.

Where would be appropriate to place the code? Is my approach incorrect to the matter?

Upvotes: 0

Views: 525

Answers (1)

Soviut
Soviut

Reputation: 91515

Trying to use threading to get around blocking processes like web servers is an exercise in pain. I've done it before and it's fragile and often yields unpredictable results.

A much easier idea is to create a separate worker that runs in a totally different process that you start separately. It would have the same database access and could even use your Django models. This is how hosts like Heroku approach this problem. It comes with the added benefit of being able to be tested separately and doesn't need to run at all while you're working on your main Django application.

These days, with a multitude of virtualization options like Vagrant and containerization options like Docker, running parallel processes and workers is trivial. In the wild they may literally be running on separate servers with your database on yet another server. As was mentioned in the comments, starting a worker process could easily be delegated to a separate Django management command. This, in turn, can be fairly easily turned into separate worker processes by gunicorn on your web server.

Upvotes: 4

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