====== Request for Comments: FPM SAPI inclusion ======
  * Version: 1.0
  * Date: 2010-03-22
  * Author: Antony Dovgal <tony.at.daylessday.dot.org>
  * Status: Implemented in PHP 5.3
  * First Published at: http://wiki.php.net/rfc/fpm

This RFC discusses FPM SAPI and its inclusion to the core PHP distribution.

===== Introduction =====

FPM (FastCGI Process Manager) is an alternative PHP FastCGI implementation with some 
additional features (mostly) useful for heavy-loaded sites.

These features include:
  * advanced process management with graceful stop/start;
  * ability to start workers with different uid/gid/chroot/environment, listening on different ports and using different php.ini (replaces safe_mode);
  * stdout & stderr logging;
  * emergency restart in case of accidental opcode cache destruction;
  * accelerated upload support;
  * "slowlog" - logging scripts (not just their names, but their PHP backtraces too, using ptrace and similar things to read remote process' execute_data) that are executed unusually slow;
  * fastcgi_finish_request() - special function to finish request & flush all data while 
continuing to do something time-consuming (video converting, stats processing etc.);
  * dynamic/static child spawning
  * basic SAPI status info (similar to Apache mod_status) 
  * XML-based config file which contains configuration for different process pools with different configuration settings (see [[http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3_FPM/sapi/fpm/php-fpm.conf.in?revision=292487&view=markup|this]] for example)
FPM uses BSD-licensed libevent (this is the only external requirement) to handle connections and manage its children.

==== Why do we need FPM? ====

FastCGI becomes more and more popular these days as people tend to realize that 'light' HTTP servers (lighttpd, nginx and the like) are much more efficient on heavy-loaded frontends than traditional Apache.

The FastCGI implementation in sapi/cgi requires third-party applications like spawn-fcgi or mod_fcgi to manage its processes and is a 'core' implementation of FastCGI protocol lacking a lot of features that are crucial for many complex real-life applications.

===== Proposal and Patch =====

FPM is ready to be merged from PHP_5_3_FPM branch in the official PHP SVN. 
All the FPM code is concentrated in sapi/fpm and no additional patches are required.

http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3_FPM/sapi/fpm/

===== Changelog =====

tony - 2010-03-22 - initial RFC version.