predis: Error while reading line from the server

We’re seeing the following error quite a lot in our application and struggling to understand why

Error while reading line from the server. [tcp://aws-domain:port] {"exception":"[object] (Predis\\Connection\\ConnectionException(code: 0): Error while reading line from the server. [tcp://aws-domain:port] at /app/vendor/predis/predis/src/Connection/AbstractConnection.php:155)"} []

Do you have any tips on how to debug this sort of issue to see what the cause was? We have full stack traces in Sentry but there doesn’t seem to be a pattern of when the error occurs.

Things we’ve tried

Set the redis.default.read_write_timeout value to 0 in Laravel (/config/database.php)
Disabled php artisan horizon:snapshot, this almost always resulted in the error appearing

Setup

Heroku Redis (Hobby dev)
laravel/laravel (5.5.40) d724ce0aa61bbd9adf658215eec484f5dd6711d6
laravel/horizon (v1.2.3) 36ef9e2d6e09e617cf801050326a69e876ff5535
predis (v1.1.1) f0210e38881631afeafb56ab43405a92cafd9fd1
PHP 7.2.5 (cli) (built: Apr 25 2018 03:07:35) ( NTS ) Copyright © 1997-2018 The PHP Group Zend Engine v3.2.0, Copyright © 1998-2018 Zend Technologies with Zend OPcache v7.2.5, Copyright © 1999-2018, by Zend Technologies

About this issue

Original URL
State: closed
Created 6 years ago
Comments: 21

Most upvoted comments

You can add the scheme to the redis config in the config/database.php:

'redis' => [

        'client' => 'predis',

        'default' => [
            'scheme' => 'tls',
            'host' => env('REDIS_HOST', '127.0.0.1'),
            'password' => env('REDIS_PASSWORD', null),
            'port' => env('REDIS_PORT', 6379),
            'database' => 0,
        ],

    ],

+17

homeoftheunits on Dec 17, 2019

https://github.com/laravel/framework/issues/25039#issuecomment-491541751

perhaps predis should check if the connection is still alive for each new request?

keevitaja on May 12, 2019

I got the resolution to the problem. So, there is a limit to ports that a application server can connect to a particular application on another machine. These ports were getting exhausted. We increased the limit and the problem got resolved.

How we got to know about this problem ? In php, we were getting “Cannot assign requested address” error while creating a socket (error code 99).

romilgoel on Jun 7, 2018

We had been having issue. After check the above and also checking our predis version change, it turns out it was just that we had been filling all the memory. We had been using Laravel and our TTL for sessions was way to high + some DDOS attack meant it was completely full. Either drop the TTL to 1 day so all those attack sessons drop off or increase the memory should do the trick. 👍

MPJHorner on Nov 11, 2021

I was able to fix this issue by switching to phpredis. Had to prefix the url to my managed DigitalOcean redis instance with tls:// but other than that everything seems to be functioning just fine. May not be solution I was hoping for but at least it works without error now.

lockhinator on Nov 14, 2019

I tried to set read_write_timeout to 0 or -1 and I’m also getting Error 500 in Horizon. I’m using a DigitalOcean Managed Redis instance.

mezuky04 on Oct 25, 2019

Unfortunately I haven’t had any luck with setting the read_write_timeout to 0 or -1 as when I do so, my whole app immediately Error 500’s. Any other solutions?

roberttolton on Oct 18, 2019

@romilgoel I’m not the best person to ask but based on findings over the last few days check that your Redis server has enough space.

I’m using Heroku Redis and finding that the hard limits (for Redis client connections and memory) can cause things to not work when deployed as they do locally.

Try using redis-cli and running the various commands to understand what your server’s state is

carltondickson on May 24, 2018