title: Spring boot/Amazon PostgreSQL RDS connection pool issue
body: <p>I am troubleshooting an issue with a Spring Boot app connecting to a PostgreSQL database.  The app runs normally, but under fairly moderate load it will begin to log errors like this:</p>
  
  <pre><code>java.sql.SQLException: Timeout after 30000ms of waiting for a connection.  
  </code></pre>
  
  <p>This is running on an Amazon EC2 instance connecting to a PostgreSQL RDS.  The app is configured like the following:</p>
  
  <pre><code>spring.datasource.url=jdbc:postgresql://[rds_path]:5432/[db name]
  spring.datasource.username=[username]
  spring.datasource.password=[password]
  spring.datasource.max-active=100
  </code></pre>
  
  <p>In the AWS console, I see 60 connections active to the database, but that is across several Spring Boot apps (not all this app).  When I query the database for current activity using pg_stat_activity, I see all but one or 2 connections in an idle state.  It would seem the Spring Boot app is not using all available connections?  Or is somehow leaking connections?  I'm trying to interpret how pg_stat_activity would show so many idle connections and the app still getting connection pool time outs.  </p>