caching - Python in-memory cache with time to live

Question

I have multiple threads running the same process that need to be able to to notify each other that something should not be worked on for the next n seconds its not the end of the world if they do however.

My aim is to be able to pass a string and a TTL to the cache and be able to fetch all the strings that are in the cache as a list. The cache can live in memory and the TTL's will be no more than 20 seconds.

Does anyone have a any suggestions for how this can be accomplished?

Answer 1

The OP is using python 2.7 but if you're using python 3, ExpiringDict mentioned in the accepted answer is currently, well, expired. The last commit to the github repo was June 17, 2017 and there is an open issue that it doesn't work with Python 3.5

As of September 1, 2020, there is a more recently maintained project cachetools.

pip install cachetools

from cachetools import TTLCache

cache = TTLCache(maxsize=10, ttl=360)
cache['apple'] = 'top dog'
...
>>> cache['apple']
'top dog'
... after 360 seconds...
>>> cache['apple']
KeyError exception raised

ttl is the time to live in seconds.