How to store easily python usable read-only data structures in shared memory
python, shared-memory, uwsgi, wsgi
Solution
This post by @modelnine on StackOverflow provides a really great comprehensive answer to this question. As he mentioned, using threads rather than process-forking in your webserver can significantly lesson the impact of this. I ran into a similar problem trying to share extremely-large NumPy arrays between CLI Python processes using some type of shared memory a couple of years ago, and we ended up using a combination of a sharedmem Python extension to share data between the workers (which proved to leak memory in certain cases, but, it's fixable probably). A read-only `mmap()` technique might work for you, but I'm not sure how to do that in pure-python (NumPy has a memmapping technique explained here). I've never found any clear and simple answers to this question, but hopefully this can point you in some new directions. Let us know what you end up doing!
Problem
I have a python process serving as a WSGI-apache server. I have many copies of this process running on each of several machines. About 200 megabytes of my process is read-only python data. I would like to place these data in a memory-mapped segment so that the processes could share a single copy of those data. Best would be to be able to attach to those data so they could be actual python 2.7 data objects rather than parsing them out of something like pickle or DBM or SQLite. Does anyone have sample code or pointers to a project that has done this to share?