Django Channel - Redis integration error : aioredis.errors.ReplyError: ERR unknown command 'EVAL'

Question

I am new to Django channels and following the tutorial ( https://channels.readthedocs.io/en/latest/tutorial/part_2.html)

As Redis does not support Windows 7 I downloaded Redis version 2.4 from (https://github.com/dmajkic/redis/downloads)

When I try to access the Redis from Django shell I got error as mentioned in the subject.

$ python3 manage.py shell
>>> import channels.layers
>>> channel_layer = channels.layers.get_channel_layer()
>>> from asgiref.sync import async_to_sync
>>> async_to_sync(channel_layer.send)('test_channel', {'type': 'hello'})
>>> async_to_sync(channel_layer.receive)('test_channel')      # ERROR OCCURED AFTER THIS STEP

As you can see below, the Redis folder , it start dev server at port 6379.

Eval is available since Redis 2.6. Redis 2.4 is close to 10 years old - it's kind of expected that modern frameworks have moved away from an unsupported platform and unsupported release. — user1600649
– user1600649, Commented Jul 27, 2020 at 11:17
Downloaded Redis 2.4 from (sourceforge.net/projects/redis) : but got new errorm ,aioredis.errors.ReplyError: ERR unknown command 'BZPOPMIN'. — Anoop K George
– Anoop K George, Commented Jul 27, 2020 at 11:28
github.com/django/channels_redis#dependencies -> Redis >= 5.0. You can run channels with an another layers backend but the tutorial uses redis. — user1600649
– user1600649, Commented Jul 27, 2020 at 11:35

Dharman · Accepted Answer · 2020-08-28 23:27:53Z

11

I had the same problem following the same tutorial, including a similar and older project that suddenly stopped working ... The following change solved my problem:

Before:

CHANNEL_LAYERS = {
    'default': {
       'BACKEND': 'channels_redis.core.RedisChannelLayer',
       'CONFIG': {
            'hosts': [('127.0.0.1', 6379)]
        },
    },
}

Solution:

CHANNEL_LAYERS = {
    "default": {
        "BACKEND": "channels.layers.InMemoryChannelLayer"
   }
}

Source: https://channels.readthedocs.io/en/latest/topics/channel_layers.html#in-memory-channel-layer

edited Aug 28, 2020 at 23:27

Dharman♦

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answered Aug 28, 2020 at 23:22

Gabriel

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5 Comments

jitesh2796 Over a year ago

hey! thanks a lot.. I was also facing the same challenge for a long time.. and most of the time its just such trivial things!

coderboy Over a year ago

Thanks so much dude, i have been trubleshooting this since morning before i came across your solution. Thanks a bunch

jitesh2796 Over a year ago

hey, I changed the layer settings earlier to InMemoryChannelLayer and it was working fine until recently. And I came across this documentation which says not to use In memory config in production. So I'm back to EVAL error. Any other possible solution?

Klaas van Schelven Over a year ago

This is basically a non-solution given that InMemoryChannelLayer does not work for most production setups (i.e. any setup with more than a single server thread)

dormant Over a year ago

InMemoryChannelLayer is good for development purposes. i can't get redis channel layer to work at the moment, so I will use it. but ultimately needs to be switched to redis

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