I spent part of the sunday solving the Dining Philosophers using Go. The given solution is based in the description for the problem present in The Little Book of Semaphores:

The Dining Philosophers Problem was proposed by Dijkstra in 1965, when dinosaurs ruled the earth. It appears in a number of variations, but the standard features are a table with five plates, five forks (or chopsticks) and a big bowl of spaghetti.

There are some constraints:

• Only one philosopher can hold a fork at a time
• It must be impossible for a deadlock to occur
• It must be impossible for a philosopher to starve waiting for a fork
• It must be possible for more than one philosopher to eat at the same time

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Extracted from Django docs: “memory isn’t intended for permanent data storage, so don’t rely on memory-based caching as your only data storage. Without a doubt, none of the Django caching backends should be used for permanent storage”.

Here is the lesson: don’t rely on caching. Cache doesn’t exist to make applications work, it exists to make them faster and/or more scalable. Use a cache system as permanent storage is such a bad idea, except when you’re not using it for caching (what is not the case here). Cache is a shortcut for a path that might be painful to follow, but you still should not rely on cache. You must be able to traverse the path without the cache.