By using mod_status to examine server load, you can retrieve valuable information that can help tune the overall server. You can use HSLAB HTTP Monitor software for it.
The command apachectl status also provides a quick way of examining the server status. If the output does not consistently show available workers, it would be best to increase the MinSpareServers or MinSpareThreads value (on threaded MPMs for Apache 2.0). You may need to increase the MaxClients value accordingly.
For ApacheTL Status and MinSpareThreads Support. Click here.