title: Airflow creates too many connections and crashes MySQL RDS server
body: <p>I am using Airflow connections to pull and process data from an RDS SQL instance. The problem is that the process is generating over 21 connections (though my concurrency is set to 4 in the cfg file) and the RAM is overloading. I wouldn't expect to have any more than 6 - 8 connections at a time based on how I've set the process up. Is there a good cfg file setting or admin panel option that will allow me to control this behavior? I have tried updated <code>sql_alchemy_pool_recycle</code> but that hasn't fixed the problem. </p>
  
  <p><a href="https://i.stack.imgur.com/kz6JF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/kz6JF.png" alt="enter image description here"></a></p>
  
  <p>You can see where the system performance starts tanking on the gant chart as the number of connections increase and the RAM on the RDS instance saturates: </p>
  
  <p><a href="https://i.stack.imgur.com/o0gDR.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/o0gDR.png" alt="enter image description here"></a></p>