title: Tomcat fails on heavy load
body: <p>I'm running a heavy db-based GWT application on a debian VPS using tomcat server 7 (&amp; JRE 1.6). My app contains a lot of java servlets which communicate with MySQL5 database via a tomcat connection pool (without connection pooling mysql will crash within less than 3 minute!)<br/>
  My app works nice while there is no heavy load on tomcat server, but when number of online users &amp; their requests increase, tomcat server fails <b>with no useful log or error message</b>(I just get a connection timeout error when I want to access any of web applications running on tomcat) &amp; this problem exists till I reset my tomcat server. I know that I've NO memory limitation on my VPS nor any MySQL connection problem, so I really don't know that causes this situation :(<br/>
  This is host tag in server.xml (I've many of these virtual hosts, but the host tag of all is similar)</p>
  
  <pre><code>&lt;Host name="sub1.mydomain.com" appBase="/var/www/sites/gwt_app" &gt;
  
      &lt;Context path="" reloadable="true" docBase="myDocBase" 
       xmlValidation="false" xmlNamespaceAware="false" crossContext="true" &gt;
  
      &lt;Resource name="jdbc/mysql/db" auth="Container" type="javax.sql.DataSource"
  
      initialSize="3" maxActive="50" maxIdle="10" 
      maxWait="15000" removeAbandoned="true" removeAbandonedTimeout="120"
      validationQuery="select now();"
  
      username="user_1" password="pass" driverClassName="com.mysql.jdbc.Driver"
      url="jdbc:mysql://localhost:3306/db_1?useUnicode=true&amp;amp;characterEncoding=UTF-8&amp;amp;characterSetResults=UTF-8&amp;amp;connectionCollation=UTF8_PERSIAN_CI&amp;amp;noAccessToProcedureBodies=true"
      /&gt;
      &lt;/Context&gt;
  
      &lt;Valve className="org.apache.catalina.valves.AccessLogValve" directory="/var/www/sites/gwt_app_logs"  prefix="tomcat_access_" suffix=".log" pattern="common" resolveHosts="false"/&gt;
  &lt;/Host&gt;
  </code></pre>
  
  <p>any idea?</p>