Sometimes you may want an application to monitor its own configuration file and reload it when it is altered. But you don't want to restart the server for these changes to take effect. The solution is to use dynamic configuration files.
Dynamic configuration files are especially useful when you want to provide administrators with a configuration tool that modifies an application on the fly. This approach eliminates the need to provide shell access to the server. It can also prevent typos, because the administration program can verify the submitted modifications.
It's possible to get away with Apache::Reload and still have a similar small overhead for the stat( ) call, but this requires the involvement of a person who can modify httpd.conf to configure Apache::Reload. The method described next has no such requirement.