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Caching Long-Running Function Results

written by Eric J. Ma on 2019-10-18 | tags: python tips optimization packages

I found this nifty tool for caching the results of long-running functions: cachier. This is useful when we’re building, say, Python applications for which quick interactions are necessary, or for caching the results of a long database query.

How do we use it? Basically it’s nothing more than a decorator!

Let’s imagine I have a long-running function as below.

def long_running_function(arg1, arg2):
    # stuff happens
    return result

Turns out, if you have a need to cache the result in a lightweight fashion, you can simply add cachier:

from cachier import cachier

def long_running_function(arg1, arg2):
    # stuff happens
    return result

The result is stored in your home directory, so the cache is accessible to you.

One nice thing cachier also offers is the ability to set a time duration after which the cache goes stale. This can be useful in situations where you know that you need to refresh the cache, such as a database query that may go stale because of new data added into it. This is done by specifying the stale_after keyword argument:

from cachier import cachier
from datetime import timedelta

# Re-cache result after 1 week.
def long_running_function(arg1, arg2):
    # stuff happens
    return result

If you need to reset the cache manually, you can always do:


There are other advanced features that cachier provides, and so I’d encourage you to go and take a look at it!

Cite this blog post:
    author = {Eric J. Ma},
    title = {Caching Long-Running Function Results},
    year = {2019},
    month = {10},
    day = {18},
    howpublished = {\url{}},
    journal = {Eric J. Ma's Blog},
    url = {},

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