ActiveRecord: how to reconnect to PostgreSQL automatically when connection drops?

Question

I am using ActiveRecord with Sinatra and PostgreSQL. When the database connection drops (due to temporary network failure or postgres server restarting), my app doesn't re-acquire connection automatically. I'll have to restart the app in order to connect to postgres again. I remember I didn't have this problem when I was using Rails in another project.

Do I need to put some configuration or code to tell ActiveRecord to reconnect to PostgreSQL automatically?

Answer 1

ActiveRecord::Base.verify_active_connections! has removed back in 2012 in rails commit 9d1f1b1ea9e5d637984fda4f276db77ffd1dbdcb. so we can't use that method.

sentences below is my result of short investigation. I am no experts in rails activerecord. so listen with caution. (but hope this helpful)

comment in connection_pool.rb said

  # 1. Simply use ActiveRecord::Base.connection as with Active Record 2.1 and
  #    earlier (pre-connection-pooling). Eventually, when you're done with
  #    the connection(s) and wish it to be returned to the pool, you call
  #    ActiveRecord::Base.clear_active_connections!. This will be the
  #    default behavior for Active Record when used in conjunction with
  #    Action Pack's request handling cycle.

so maybe you (and I. I have a same situation just like you) have to return connection to pool.

and to return connection to pool in sinatra as Action Pack's request handling cycle, use ActiveRecord::ConnectionAdapters::ConnectionManagement

use ActiveRecord::ConnectionAdapters::ConnectionManagement

and then as stated in rails commit 9d1f1b1ea9e5d637984fda4f276db77ffd1dbdcb we are using a different way as in this line, always checkout_and_verify when using Basae.connection by obeying action pack lifecycle.

  def connection
    # this is correctly done double-checked locking
    # (ThreadSafe::Cache's lookups have volatile semantics)
    @reserved_connections[current_connection_id] || synchronize do
      @reserved_connections[current_connection_id] ||= checkout
    end
  end

Answer 2

UPDATED 2019-01-11 As of Rails 4.2 I have to use

ActiveRecord::Base.clear_active_connections!

and ActiveRecord will reconnect on next query. Works also from Rails console, which is rather convenient