Sidekiq - could not obtain a database connection within 5.000 seconds

Question

I get the following warning with Rails 4 and Sidekiq on os x on development

10:13:39 worker.1 | 2014-09-22T07:13:39.857Z 86981 TID-oug0oog10 WARN: could not obtain a database connection within 5.000 seconds (waited 5.002 seconds)
10:13:39 worker.1 | 2014-09-22T07:13:39.857Z 86981 TID-oug0oog10 WARN: /Users/me/.rvm/gems/ruby-2.1.3/gems/activerecord-4.1.6/lib/active_record/connection_adapters/abstract/connection_pool.rb:190:in `block in wait_poll'

I read other answers that say to reduce the concurrency I give to sidekiq to allow more for other things, but with

worker: bundle exec sidekiq -c 10 

it still doesn't work

I am using Postgres.app

What should the numbers/concurrency be in localhost?

Answer 1

I set database pool to sidekiq concurrency and now it works for me.

bundle exec sidekiq -c 10

in my database.yml

development:
  adapter: postgresql
  ...
  host: localhost
  pool: 10

Answer 2

The probem is related to the fact that database pool should be 'sidekiq_concurrency' + 2. If you put this into your sidekiq initializer you will solve the problem in general:

Sidekiq.configure_server do |config|
     config = ActiveRecord::Base.configurations[Rails.env] ||
         Rails.application.config.database_configuration[Rails.env]
     config['pool'] = Sidekiq.options[:concurrency] + 2
     ActiveRecord::Base.establish_connection(config)
     Rails.logger.debug("Connection Pool size for Sidekiq Server is now: #{ActiveRecord::Base.connection.pool.instance_variable_get('@size')}")
end

Answer 3

Database connection size should be one plus the concurrency if we are using rails < 5.2 . Here is the corresponding GitHub issue. https://github.com/mperham/sidekiq/issues/4252

If there are 5 threads then the db pool size should be 6 in rails < 5.2 version