title: Thread local behaviour in spring boot
body: <p>As we know Tomcat has approx 200 threads and Jetty has some default count threads in their respective thread pools. So if we set something in a <code>ThreadLocal</code> per request, will it be there in the thread for life time or will Tomcat clear the <code>ThreadLocal</code> after each request. </p>
  
  <p>If we set something in userContext in a filter do we need to clear it every time the filter exits?  </p>
  
  <p>Or will the web server create a new thread every time, if we don't have a thread pool configuration?</p>
  
  <pre><code>public static final ThreadLocal&lt;UserContextDto&gt; userContext = new ThreadLocal&lt;&gt;();
  </code></pre>