Signal Heroku - from your codebase - to restart the dynos.

ApplicationController.rb

# This snippet can be included in ApplicationController.rb
if Rails.env.production?
  rescue_from StandardError do |error|
    # if it is an unrecoverable error, send a signal to heroku
    # to restart the infrastructure
    if error.message =~ /deadlock; recursive locking/
      hclient = PlatformAPI.connect_oauth(ENV["HEROKU_API_TOKEN"])
      heroku_app, dyno = "name-of-your-app", hclient.dyno
      # avoid sending the signal more than once
      if dyno.list(heroku_app).dig(0, "state") === "up"
        heroku_app.restart_all(heroku_app)
      end
    end
    server_error
  end
end

def server_error
  render "common/500", status: :internal_server_error
end