title: How to find current connection pool size on heroku
body: <p>We have a rails 3.2(.11) app with many dynos running on the heroku bamboo stack, connecting to a MySQL RDS server. There seem to be some issues with our current database connections, so we are trying to debug exactly how many connections each dyno is spinning up. I know I can set the size of a connection pool in the <code>DATABASE_URL</code> config on heroku, but can't seem to find out how many connections are currently being used by default.</p>
  
  <p>Two main questions:</p>
  
  <p>1) How can I find the size of the connection pool used by heroku?</p>
  
  <p>2) Is there any reason why a dyno would need a connection pool size greater than 1? My understanding is that rails can only execute 1 request at a time so one database connection should be all that is needed as far as I can see.</p>