Django_redis lock fails with UnpicklingError

Question

In one place of my code, I use django_redis to update cache with a lock:

from django.core.cache import cache
with cache.lock('hello'):
    # do stuff

In another place, I check whether cache is not locked using:

if not cache.get('hello'):
    # do other stuff

However, when lock is set, get call fails with UnpicklingError: invalid load key, 'f'. Why is this happening? What am I doing wrong?

You can reproduce this behaviour with this snippet:

from django.core.cache import cache
with cache.lock('hello'):
    cache.get('hello')

score 2 · Answer 1 · answered Sep 24 '18 at 09:04

it's not very obviously, but as i understand your lock_key and cache_key must not be the same. for example this code:

cache_key = 'hello'
with cache.lock(cache_key):
    cache.get(cache_key)

raise UnpicklingError: invalid load key....

In the same time this code:

cache_key = 'hello'
lock_key = cache_key + '_lock'
with cache.lock(lock_key):
    cache.get(cache_key)

works as you want.

1 Answers1