Why FastCGI + Chroot?
First of all, mod_fastcgi spawns an application called “fcgi-pm” (FastCGI Process Manager), it in turn spawns the persistent FastCGI enabled application. Fcgi-pm pipes information back and forth between Apache and the FastCGI enabled application. This way, only one running process is needed to execute PHP scripts, where previously we needed one CGI application running for each script that was processing. This saves on CPU, speed, and memory, since the binary is preloaded, and ready to process scripts. Also, as discussed above, since it is persistent in memory, eAccelerator or APC will work with it, caching compiled scripts in memory. Thus, Eliminating compile time and disk access. Persistent MySQL connections will also function correctly with this setup. These are all major improvements in CPU usage and speed of application of scripts. Speed improvement is dependent on the script, but the faster it executes and gets out of the way, the faster the next request can be processed. As to th
