On Thu, 15 Oct 2020 22:31:25 -0600 Carl Meyer <c...@oddbird.net> wrote: > On Thu, Oct 15, 2020 at 3:33 PM David Mertz <me...@gnosis.cx> wrote: > > So the use case needs to be: > > > > * Function operates on large objects > > * Function operates on large, immutable objects > > * Function never takes literal or computed arguments (i.e. not > > `fun(big1+big2)`) > > * Large immutable objects are deleted selectively (OK, this is plausible) > > * The performance hit of clearing entire cache is not suitable > > One real-world use case I've seen personally that meets all these > criteria is per-request memoization of expensive work in a server > application (using an `lru_cache`-like decorator on functions taking > the request as an argument.) The request object plus things hanging > off it can be quite large, it's often effectively immutable (at least > inasmuch as the functions so decorated care), it's desirable for all > cached data for a request to expire as soon as handling for the > request is finished, but you wouldn't want to fully clear the caches > (e.g. the application may handle multiple requests concurrently, so > other requests may still be in-flight.)
A common recipe for that is simply to set a custom attribute on the request: request._myapp_cached_data = ... It's probably much faster than caching through a dict, as well. Regards Antoine. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/22I32ZJD6YD3ONOKJJ75YQDCHTJ5EWKF/ Code of Conduct: http://python.org/psf/codeofconduct/
