Apache closes idle AJP/1.3 connections to Tomcat server. However, for some reasons, these connection close requests do not result in closing and clearing of corresponding connections at the Tomcat server end. As a result, over a period of time, there will be too many open connections at the Tomcat server end resulting in queuing/rejection of new connection requests from the Apache server. This issue is mostly caused by incorrect firewall rules.
The manifestation of this issue is OpenSpecimen UI/API become unresponsive.
To resolve this issue, please follow below steps:
1. Edit $TOMCAT_HOME/conf/server.xml and search for below line:
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443"/>
2. Add ConnectionTimout attribute as shown below. This will ensure the AJP connections at Tomcat end are closed after 5 minutes of continuous idleness.
<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" connectionTimeout="300000"/>
3. Save the server configuration file.
4. Restart Tomcat server.