I'm getting "ERR max number of clients reached" for my Redis, how can I avoid this?

Issue

You're seeing the error ERR max number of clients reached and running out of connections.

Resolution

There are several things you can do to avoid this, such as using a connection pooler to reduce the number of connections, setting an appropriate connection timeout to close inappropriate idle connections.
Here is a blog post, talking about above things, and also many useful tips. Please check it out!
https://blog.heroku.com/real-world-redis-tips