PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI
implementation with some additional features useful for sites
of any size, especially busier sites.

These features include:

* Adaptive process spawning (NEW!)
* Basic statistics (ala Apache's mod_status) (NEW!)
* Advanced process management with graceful stop/start
* Ability to start workers with different uid/gid/chroot/environment
  and different php.ini (replaces safe_mode)
* Stdout & stderr logging
* Emergency restart in case of accidental opcode cache destruction
* Accelerated upload support
* Support for a "slowlog"
* Enhancements to FastCGI, such as fastcgi_finish_request() - a special
  function to finish request & flush all data while continuing to do
  something time-consuming (video converting, stats processing, etc.)

... and much more.

It was not designed with virtual hosting in mind (large amounts of pools)
however it can be adapted for any usage model.