ActiveRecord in Rails 5.2 discards connection pools after fork.

config/unicorn.conf.rb

@@ -205,10 +205,6 @@ before_fork do |server, worker|
 
   end
 
-  RailsMultisite::ConnectionManagement.each_connection do
-    ActiveRecord::Base.connection_pool.disconnect!
-  end
-
   $redis._client.disconnect
 
   # Throttle the master from forking too quickly by sleeping.  Due

lib/discourse.rb

@@ -436,8 +436,6 @@ module Discourse
   # in a bad state
   def self.after_fork
     # note: all this reconnecting may no longer be needed per https://github.com/redis/redis-rb/pull/414
-    current_db = RailsMultisite::ConnectionManagement.current_db
-    RailsMultisite::ConnectionManagement.establish_connection(db: current_db)
     MessageBus.after_fork
     SiteSetting.after_fork
     $redis._client.reconnect