Shared object across threads in Flask [duplicate]

问题

This question already has answers here:

Are global variables thread safe in flask? How do I share data between requests? (2 answers)

Store large data or a service connection per Flask session (1 answer)

Concurrency-safe way to initialize global data connections in Flask (1 answer)

Closed 10 months ago.

I have a Web server that runs a Flask app.

I also need to implement a Google pub/sub subscriber, using a "Pull" strategy. This basically means I have to instanciate a subscriber, which will constantly poll for messages from its subscription. When it finds a message, it calls a function.

Currently, I have everything mixed in: my app.py script with its endpoints and the instanciation of the subscriber.

What I am unsure about is: can I be sure that there will only be one subscriber instanciated? Basically, when does app.py get executed? I have been trying to figure this out from the Flask docs but wouldn't mind some insights.

And the real question is: how can I have a Flask web server AND instanciate my subscriber correctly?

Edit about "Possible duplicate" issue: I don't believe this is a duplicate: while I have looked at this question before posting this and it gave me good information, it was focused on storing variables in a database instead of as global variables. My problem is different: I need to have this object running continuously so I have to find a way to make it work.

回答1:

I would suggest that you take a look at flask's factory documentation for the preferred way to do this. Essentially, have your subscriber instantiated at global scope in a separate file, and import that file inside of your create_app function and wherever else it is needed.

来源：https://stackoverflow.com/questions/54637324/shared-object-across-threads-in-flask