The Apache Web server controls concurrent connections (simultaneous requests) using the MaxClient directive. To enable an Apache Web server to handle more than 256 concurrent connections, update the value of MaxClient in the httpd.conf file.
If more than 256 concurrent connections are established with the Apache Web server, connections over the 256 limit are queued, typically based on the value of the ListenBacklog directive. If you increase the value of MaxClient, you must also increase the value of the ServerLimit directive to the number of Apache processes in the Web server. By default, MaxClient is set to 256; ListenBacklog is set to 511.
Relay Server versions 12.0.x and higher incorporate a semaphore manager to manage semaphore use by the Relay Server. If you change the values of MaxClient and ServerLimit, you need not increase the "semaphore sets" in the system.
To increase the number of concurrent connections, add the following lines to httpd.conf:
ServerLimit 1000 MaxClient 1000
Other Apache directives that you can adjust for busy Web servers include:
MaxSpareServers MinSpareServers StartServers