CODEWITHSUNDEEP
pythonflaskmultiprocessingwsgigunicorn
Doctor J
Doctor J

Reputation: 6312

Sharing static global data among processes in a Gunicorn / Flask app

I have a Flask app running under Gunicorn, using the sync worker type with 20 worker processes. The app reads a lot of data on startup, which takes time and uses memory. Worse, each process loads its own copy, which causes it to take even longer and take 20X the memory. The data is static and doesn't change. I'd like to load it once and have all 20 workers share it.

If I use the preload_app setting, it only loads in one thread, and initially only takes 1X memory, but then seems to baloon to 20X once requests start coming in. I need fast random access to the data, so I'd rather not do IPC.

Is there any way to share static data among Gunicorn processes?

Upvotes: 22

Views: 13190

Answers (2)

aaa90210
aaa90210

Reputation: 12083

Memory mapped files will allow you to share pages between processes.

https://docs.python.org/3/library/mmap.html

Note that memory consumption statistics are usually misleading and unhelpful. It is usually better to consider the output of vmstat and see if you are swapping a lot.

Upvotes: 7

Miguel Grinberg
Miguel Grinberg

Reputation: 67479

Assuming your priority is to keep the data as a Python data structure instead of moving it to a database such as Redis, then you'll have to change things so that you can use a single process for your server.

Gunicorn can work with gevent to create a server that can support multiple clients within a single worker process using coroutines, that could be a good option for your needs.

Upvotes: 3

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