The Apache Web server controls concurrent connections (simultaneous requests) using the max clients directive. By default, the max clients directive is set to 256. If more than 256 concurrent connections are established with the Apache Web server, connections over the 256 limit are queued normally based on the listen backlog directive. By default, the listen backlog directive is set to 511.

For the Apache Web server to handle more than 256 concurrent connections, the max clients directive needs to be set in the httpd.conf file. If the max client directive is increased, the server limit directive must also be modified to increase the number of Apache processes in the Web server.

Relay Server 12.0.x incorporates a semaphore manager to manage semaphore use by the Relay Server. As a result, there is no need to increase the "semaphore sets" in the system when changing the max clients and server limit directives.

To increase the number of concurrent connections, add the following lines to httpd.conf:

ServerLimit 1000
MaxClient 1000

Other Apache directives that can be adjusted in busy Web servers include:

MaxSpareServers 
MinSpareServers
StartServers