Detailed explanation of the difference between FastCGI and php-fpm

What is CGI? CGI is a protocol and has nothing to do with processes or anything like that. The web server (such as nginx) is just a distributor of content.

For example, 1) If the request is /*.html static data, then the web server will find this file in the file system and send it to the browser. 2) If the request is for /*.php dynamic data, nginx needs to find a PHP parser to process it according to the configuration file, then it will simply process the request and hand it over to the PHP parser.

What data will nginx pass to the PHP parser? URLs, query strings, POST data, and HTTP headers will all be included. Therefore, CGI is a protocol that stipulates what data is to be transmitted and in what format to be passed to the backend for processing the request.

When the web server receives the request /*.php, it will start the corresponding CGI program, which is the PHP parser. Next, the PHP parser will parse the php.ini file, initialize the execution environment, process the request, return the processed result in the format specified by CGI, and exit the process. The web server then returns the results to the browser. 2. What is FastCGI?

Fundamentally speaking, FastCGI is used to improve the performance of CGI programs. Similar to CGI, FastCGI can also be said to be a protocol.

FastCGI is like a long-live CGI. It can be executed all the time. As long as it is activated, it will not take time to fork every time (this is the most criticized thing about CGI). fork-and-execute mode). It also supports distributed computing, that is, FastCGI programs can be executed on hosts other than the website server and accept requests from other website servers.

FastCGI is a language-independent, scalable architecture CGI open extension. Its main behavior is to keep the CGI interpreter process in memory and thus obtain higher performance.



How FastCGI works 1) The FastCGI process manager (IIS ISAPI or Apache Module) is loaded when the Web Server starts 2) The FastCGI process manager initializes itself and starts multiple CGI interpreters process (multiple php-cgi visible) and wait for connections from the Web Server. 3) When a client request reaches the Web Server, the FastCGI process manager selects and connects to a CGI interpreter. The web server sends CGI environment variables and standard input to the FastCGI subprocess php-cgi. 4) After the FastCGI sub-process completes processing, it returns standard output and error information to the Web Server from the same connection. When the FastCGI child process closes the connection, the request is processed. The FastCGI child process then waits for and handles the next connection from the FastCGI process manager (running in the Web Server). In CGI mode, php-cgi exits at this point.



In the above case, you can imagine how slow CGI usually is. Every web request to PHP must reparse php.ini, reload all extensions and reinitialize all data structures. With FastCGI, all of this happens only once, when the process starts. An added benefit is that persistent database connections work. 3. What is php-cgi?

php-cgi is the interpreter of PHP. It is just a CGI program. It can only parse requests and return results, but does not manage processes. 4. What is php-fpm?

php-fpm is the FastCGI process manager. For the specific implementation of the FastCGI protocol, it is responsible for managing a process pool to handle requests from the Web server. Currently, after PHP5.3 version, php-fpm is built into PHP.

Start up php-fpm:

/usr/local/php/sbin/php-fpm

Close down php-fpm:

pkill php -fpm

or

kill -INT `cat /usr/local/php/var/run/php-fpm.pid`

php-fpm restart:

kill -USR2 `cat /usr/local/php/var/run/php-fpm/pid`

Check whether php-fpm started successfully:

netstat -tunpl | grep 90001 or

ps aux | gerp php-fpm

Start php-fpm on boot:

Open /ect/rc.local and join /usr/local/php/ sbin/php-fpm

Signal: INT, TERM Terminate immediately
QUIT Terminate smoothly

USR1 Reopen the log file

USR2 Reload all worker processes smoothly and restart Loading logs and binary modules

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Implementing the FastCGI protocol in php and in-depth understanding

Comparing CGI , FastCGI, the difference between PHP-CGI and PHP-FPM

PHP FastCGI process manager PHP-FPM architecture

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