config/initializers/sqlite3.rb

database.yml

# config/database.yml

# SQLite. Versions 3.8.0 and up are supported.
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem "sqlite3"
#
default: &default
  adapter: sqlite3
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 10 } %>
  retries: 100
  default_transaction_mode: immediate

development:
  primary:
    <<: *default
    database: storage/db/development.sqlite3

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  primary:
    <<: *default
    database: storage/db/test.sqlite3

performance:
  primary:
    <<: *default
    database: storage/db/performance.sqlite3

production:
  primary:
    <<: *default
    database: storage/db/production.sqlite3

sqlite3.rb

# config/initializers/sqlite3.rb

module SQLite3Configuration
  private
    def configure_connection
      super

      if @config[:retries]
        retries = self.class.type_cast_config_to_integer(@config[:retries])
        raw_connection.busy_handler do |count|
          (count <= retries).tap { |result| sleep count * 0.001 if result }
        end
      end
    end
end

ActiveSupport.on_load :active_record do
  ActiveRecord::ConnectionAdapters::SQLite3Adapter.prepend SQLite3Configuration
end