Start multiple sessions from Flask

[ryanwesslen]

Hi @MaxB!

Thanks for your question! It is a great question.

@MaxB

The only problem is once prodigy.serve() is called the application is blocked

What's the error message you're seeing? If you open your browser's developer tools, do you see a request error there? Maybe CORS related? Is there any traceback in the terminal?

@MaxB

The ticket system will than call a Flask REST API that will format the recipe string and start a webserver via prodigy.serve()

It seems your goal is to use Prodigy from a Flask application. Here's a past post on why to be cautious on running Prodigy within any other web server (like Flask):

Can't run Prodigy in Flask view function

Hey @akerestecioglu! Yes, the problem is that Prodigy will run a web server itself for most of the commands. So you shouldn't run it from inside another web server, because weird things would happen. The first thing is that if you send several requests to the same Flask view, it would try to run several servers at the same time, but I see you are already checking available ports. The next is, you will have strange issues like this if you try to start an asyncio event loop (done automatically …

@MaxB

So basically how do I start multiple prodigy session from within a single python program?

This answer can vary but have you seen this FAQ on multi-sessions/annotators? Here's an excerpt:

One option we recommend is to divide up the annotation work so that each annotator only needs to deal with a small part of the annotation scheme. For instance, if you’re working with many labels, you would start a number of different Prodigy services, each specifying a different label, and each advertising to a different URL. Prodigy can be easily run under automation, for instance within a Kubernetes cluster, to make this approach more manageable. If you do want to have multiple annotators working on one feed, Prodigy has support for that as well via named multi-user sessions. You can create annotator-specific queues using query parameters, or use the query parameters to distinguish the work of different annotators so you can run inter-annotator consistency checks.

Are you aware of multi-user sessions? If this doesn't fit your goals, definitely keep searching Prodigy support. There are 50+ issues on handling multiple sessions and hopefully it can provide you more help depending on your goals.

Hope this helps!