Apache & Tomcat ThreadsPerChild problem

Hello,
I have the following setup
(Windows Server 2012 R2) Apache 2.4 (to handle the SSL)-> Tomcat 8.0.30 -> Vaadin (7.6.6).
The application is working fine, however I have noticed that some times Apache Server shutdown and throws the following error:

[Sun Jul 10 15:43:31.436495 2016] [mpm_winnt:error] [pid 1192:tid 1312] AH00326: Server ran out of threads to serve requests. Consider raising the ThreadsPerChild setting

From that point on, the application becomes unresponsive through the Apache route (if I try through the Tomcat route on 8080 port everything works fine)...

Does anyone have any idea why this is happening? I 'm enclosing the web.xml file I am using for my Application.

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>ServiceManager</display-name>
  <listener>
        <listener-class>servicemanager.InitialApplicationSettingsLoader</listener-class>
  </listener>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <session-config>
    <session-timeout>120</session-timeout>
  </session-config>
   <context-param>
    <description>Configurations File Path (Config.ini / log4j.xml)</description>
    <param-name>application.configdirectory</param-name>
    <param-value>C:\\MySystem\\Configuration</param-value>
  </context-param>
  <context-param>
  <description>If user closes browser, the UI clears after the heartbeat</description>
  <param-name>heartbeatInterval</param-name>
  <param-value>500</param-value>
</context-param>
  <context-param>
    <param-name>closeIdleSessions</param-name>
    <param-value>true</param-value>
  </context-param>
</web-app>

Thanks
Nick

Hi,

Your apache mpm worker crashed and you need to raise your ThreadsPerChild in httpd.conf

See more here: http://httpd.apache.org/docs/2.4/mod/mpm_winnt.html