title: Connection Pool configuration / error in SonarQube
body: <p>from time to time I have the following error in my logs:</p>
  <blockquote>
  <p>Error querying database.  Cause: org.apache.commons.dbcp.SQLNestedException: Cannot get a  connection, pool error Timeout waiting for idle object</p>
  <p>The error may exist in org.sonar.core.issue.db.ActionPlanMapper</p>
  <p>The error may involve org.sonar.core.issue.db.ActionPlanMapper.findByKeys</p>
  <p>The error occurred while executing a query</p>
  </blockquote>
  <p>How should I adjust my connection pool settings so that this doesn't occur anymore?</p>
  <pre><code>sonar.jdbc.maxActive=25
  sonar.jdbc.maxIdle=5
  sonar.jdbc.minIdle=2
  sonar.jdbc.maxWait=15000
  sonar.jdbc.minEvictableIdleTimeMillis=600000
  sonar.jdbc.timeBetweenEvictionRunsMillis=30000
  </code></pre>