Quickly get memcached working in Python Django

As with most frameworks, the Django framework for Python can make use of caching to greatly improve performance for many common requests. Here we will look at using memcached as it enjoys good Django support and production use although there is also Redis support which definitely improves on memcached in some aspects such as data persistence.

  1. The first step is to install memcached on your server:
  2. RedHat Linux:

    yum install memcached

    Ubuntu / Debian Linux:

    apt-get install memcached
  3. Let Django know how to access memcached:
  4. In Django’s settings.py file, add the following line:

    'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache'
  5. Load the cache within your application
  6. from django.core.cache import cache
  7. Save the value to the cache
  8. cache.set('exampleValue',exampleValue)
  9. Retrieve the value from the cache
  10. exampleValue = cache.get('exampleValue')

The beauty being that exampleValue can be anything from a computed / database retrieved value to large blocks of static text or a URL etc.

The only problem with caches is they don’t always contain the data you expect, what if the value got flushed or hasn’t yet been stored? Lets rewrite step 5 to handle the event of the value not being available in the cache:

exampleValue = cache.get('exampleValue')
if not exampleValue:
     exampleValue = exampleValueLookup
     cache.set('exampleValue',exampleValue)

Here we see the value exampleValue being retrieved with a backup regeneration if the value has not been set. In a real application this would usually be encapsulated in a getExampleValue function or somewhere appropriate.

Advertisements

Leave a Reply