Note the need for a big DB connection pool to match worker pool size

README.md

@@ -244,6 +244,7 @@ ActionCable.server.config.log_tags = [
 
 For a full list of all configuration options, see the `ActionCable::Server::Configuration` class.
 
+Also note that your server must provide at least the same number of database connections as you have workers. The default worker pool is set to 100, so that means you have to make at least that available. You can change that in `config/database.yml` through the `pool` attribute.
 
 ## Starting the cable server