#35651: The number of Redis connections has been continuously increasing.
-------------------------------------+-------------------------------------
     Reporter:  gojuukaze            |                    Owner:  (none)
         Type:  Bug                  |                   Status:  new
    Component:  Core (Cache system)  |                  Version:  5.0
     Severity:  Normal               |               Resolution:
     Keywords:                       |             Triage Stage:
                                     |  Unreviewed
    Has patch:  0                    |      Needs documentation:  0
  Needs tests:  0                    |  Patch needs improvement:  0
Easy pickings:  0                    |                    UI/UX:  0
-------------------------------------+-------------------------------------
Changes (by gojuukaze):

 * summary:  django redis cache not really using connection pooling => The
     number of Redis connections has been continuously increasing.


Old description:

> 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.

New description:

 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 and a new connection 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#comment:1>
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