How to implement per-request in-memory "cache" of value in django

Question

I'd like to store a value from the database that isn't going to change during a request/response cycle, but gets used hundreds (potentially thousands) of times.

e.g.:

#somefile.py

def get_current_foo(request): # this gets called a lot and is currently a bottleneck
  foo = get_foo_from_db(request.blah)
  return foo

Currently I use memcached to store the value, but this thing gets called enough that even using memcached to store the value is a bottleneck (I'm profiling it as we speak). Is there a way to "cache" the value in-memory for the current request/response cycle?

( follow up from Are python "global" (module) variables thread local? )

Can you store it on the request object itself perhaps?

Martijn Pieters
– Martijn Pieters

2013-03-12 15:51:20 +00:00
Commented Mar 12, 2013 at 15:51 — Martijn Pieters
– Martijn Pieters, Commented Mar 12, 2013 at 15:51
I can't think of why not. Thanks!

B Robster
– B Robster

2013-03-12 15:52:11 +00:00
Commented Mar 12, 2013 at 15:52 — B Robster
– B Robster, Commented Mar 12, 2013 at 15:52
Possible duplicate of Per-request cache in Django?

Djizeus
– Djizeus

2016-02-07 09:09:23 +00:00
Commented Feb 7, 2016 at 9:09 — Djizeus
– Djizeus, Commented Feb 7, 2016 at 9:09

Community · Accepted Answer · 2017-05-23 12:07:33Z

4

If it is per-request data, store it on the request object itself. :-)

See Per-request cache in Django? for some techniques to do so.

edited May 23, 2017 at 12:07

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answered Mar 12, 2013 at 15:53

Martijn Pieters

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4 Comments

B Robster Over a year ago

That link seems to address caching the request itself in threadlocals, which solves a different concern (passing the request around everywhere). Since I have the request already, it seems I can just add the attribute to it, and check for it in future calls, simple enough, if i'm understanding correctly.

Martijn Pieters Over a year ago

@BenRoberts: the second answer stores things directly on the Django request; I wasn't 100% certain that you could simply do request.my_cache = cachedvalue and then test for it with getattr(request, 'my_cache', None).

B Robster Over a year ago

Ah. Got it. I'll try the basic way first and if that doesn't work, I'll go down that route.

B Robster Over a year ago

Simply setting the attribute (request.myvalue) and using getattr(request, 'myvalue', None) seems to be working fine.

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