title: Spring boot connection pool max size allows more connection than it should
body: <p>I've configured max pool size as 10 in my Spring boot 2.0 application(I'm using Hikari connection pool). I'm testing my REST API using JMeter. I am trying to simulate 500 concurrent users(Thread Group - > Thread Properties -> Number of Threads (user):500). I expect the test to fail after 20th request but my JMeter test is working perfectly. </p>
  
  <pre><code>spring.datasource.hikari.minimumIdle: 10
  spring.datasource.hikari.maximumPoolSize: 10
  spring.datasource.hikari.connectionTimeout: 30000
  spring.datasource.hikari.idleTimeout: 600000
  spring.datasource.hikari.maxLifetime: 1800000
  spring.datasource.hikari.connectionInitSql: SELECT 1 FROM DUAL
  </code></pre>
  
  <p><strong>pom.xml</strong></p>
  
  <pre><code>    &lt;dependency&gt;
          &lt;groupId&gt;com.oracle.jdbc&lt;/groupId&gt;
          &lt;artifactId&gt;ojdbc7&lt;/artifactId&gt;
          &lt;version&gt;12.1.0.2&lt;/version&gt;
      &lt;/dependency&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
          &lt;artifactId&gt;spring-boot-starter-jdbc&lt;/artifactId&gt;
      &lt;/dependency&gt;
  </code></pre>
  
  <ol>
  <li>Even thought I have maximumPoolSize 10 I am able to make 500 connection concurrently. why it is allowing?</li>
  <li>Whether my Hikari connection pool setup is wrong? i.e. do i need to disable tomcat connection pool by excluding it in pom.xml (i believe it is not required in Spring 2.0)</li>
  </ol>