问题
I have a flask application within which I have many long running asynchronous tasks (~hours). It's important that the state of these tasks is communicated with the client.
I use celery to manage the background task queue, and I'm currently trying to broadcast updates to the client from each background thread via socketIO. Is this possible? Is there a better suited strategy to achieving what I would like?
回答1:
You did not say, but I assume you plan on using Flask-SocketIO to handle the server-side SocketIO and not the official Node.js server, correct?
What you want to do can be done, but with the current version of Flask-SocketIO, the problem is that the process that hosts the Flask and Flask-SocketIO server owns the socket connections with the clients, so it is the only process that can communicate with them. At this time, Flask-SocketIO does not offer any help in sending data to clients from other processes such as Celery workers, this part you have to implement yourself. Specifically for Celery, you can have your long running tasks expose progress information that the server process can pick up and send to the clients.
I am currently working on improvements to Flask-SocketIO that will enable any process to send messages to connected clients using a Redis pub/sub backend for communication to the Flask-SocketIO server. Once this work is completed you will be able to write data to any client transparently from your Celery process.
You also ask if there is another alternative. You should also consider that the client can poll the server for status. If the updates do not need to be very frequent, then this is an option that is going to be much easier to implement. The client asks the server for status for a given task, and the server in turn asks the Celery task. I showed this approach in my Flask+Celery blog article.
来源：https://stackoverflow.com/questions/33762181/server-push-with-socketio-from-celery-task