[Django] #35651: django redis cache not really using connection pooling

[Django]

#35651: django redis cache not really using connection pooling
---------------------------+-----------------------------------------------
Reporter: gojuukaze | Type: Bug
Status: new | Component: Core (Cache system)
Version: 5.0 | Severity: Normal
Keywords: | Triage Stage: Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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I'm using `django.core.cache.backends.redis.RedisCache` as a backend for
redis, and I recently observed that the number of Redis connections has
been continuously increasing.

After debugging, I found that whenever the cache method is called, the
`RedisCacheClient `class is reinitialized, and in the `__init__` function
of `RedisCacheClient`, the connection pool is set to empty.

This causes the `_get_connection_pool` method of `RedisCacheClient` to
always create a new connection pool instead of using the existing one.

{{{
class RedisCacheClient:
def __init__(
self,
servers,
serializer=None,
pool_class=None,
parser_class=None,
**options,
):
import redis

self._lib = redis
self._servers = servers
self._pools = {} # << === set pools

def _get_connection_pool(self, write):
index = self._get_connection_pool_index(write)

#
# self._pools is is always empty.
#

if index not in self._pools:
self._pools[index] = self._pool_class.from_url(
self._servers[index],
**self._pool_options,
)
return self._pools[index]
}}}


One solution is to put `_pools` outside of `__init__` , for example：


{{{
class RedisCacheClient:

# init pool
_pools = {}

def __init__(
self,
servers,
serializer=None,
pool_class=None,
parser_class=None,
**options,
):
import redis

self._lib = redis
self._servers = servers
## self._pools={}

}}}

By the way, I am using Django 5.0.7 and running it in asynchronous mode.
--
Ticket URL: <https://code.djangoproject.com/ticket/35651>
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