What are CGI, FastCGI, php-cgi, PHP-FPM, spawn-fcgi?

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what is CGI

The CGI name is a "public Gateway Interface" (Common Gateway Interface), a tool that the HTTP server "chats" with programs on your or other machines, and its programs must be run on a network server.

CGI can be written in any language, as long as the language has standard input, output, and environment variables. such as PHP,PERL,TCL and so on.

What is fastcgi

FastCGI is like a resident (long-live) CGI, which can be executed all the time, so long as it is activated, it will not take a moment to fork once (this is the most notorious fork-and-execute mode of CGI). It also supports distributed operations where the FastCGI program can execute and accept requests from other Web servers on hosts other than the Web server.

FastCGI is a language-independent, extensible architecture for CGI open extensions whose main behavior is to keep the CGI interpreter process in memory and thus achieve high performance. As we all know, the repeated loading of CGI interpreter is the main reason of poor CGI performance, if the CGI interpreter remains in memory and accepts the FASTCGI process manager scheduling, it can provide good performance, scalability, fail-over characteristics and so on.

fastcgi and CGI features

1, such as cgi,fastcgi also have language-independent.

2, such as CGI, fastcgi in-process applications, running independently of the core Web server, provides a more secure environment than the API. (APIs link the application's code with the core Web server, which means that an application in the wrong API can corrupt other applications or core servers; The application code of a malicious API can even steal the key from another application or core server.) )

3, FASTCGI technology currently supports languages include: C + +, Java, Perl, TCL, Python, SmallTalk, Ruby and so on. Related modules are also available on popular servers such as Apache, ISS, lighttpd and more.

4, such as cgi,fastcgi does not depend on any Web server's internal architecture, so even if the server technology changes, fastcgi is still stable.

How the FastCGI works

1. Load the FASTCGI Process Manager (IIS ISAPI or Apache Module) when Web server starts

2, the FASTCGI process manager itself initializes, starts multiple CGI interpreter processes (visible multiple php-cgi) and waits for a connection from the Web server.

3. When a client request arrives at Web server, the FASTCGI process manager selects and connects to a CGI interpreter. WEB server sends CGI environment variables and standard input to the FASTCGI child process php-cgi.

4. After the fastcgi process finishes processing, the standard output and error information are returned from the same connection to the Web Server. When the fastcgi child process closes the connection, the request is processed to completion. The fastcgi child process then waits and processes the next connection from the FASTCGI process Manager (running in Web server). In CGI mode, php-cgi exits here.

In the above scenario, you can imagine how slow CGI is usually. Every Web request PHP must re-parse php.ini, reload all extensions, and initialize all data structures. With fastcgi, all of this occurs only once when the process is started. An additional benefit is that the persistent database connection (persistent connection) can work.

fastcgi of the poor

Because it is multi-process, so consumes more server memory than CGI multithreading, php-cgi interpreter consumes 7 to 25 megabytes per process, multiplying this number by 50 or 100 is a large amount of memory.

Nginx 0.8.46+php 5.2.14 (FastCGI) server under 30,000 concurrent connection, open 10 Nginx process consumes 150M memory (15M10=150m), open 64 php-cgi process consumes 1280M memory (20M 64=1280m), combined with the memory consumed by the system itself, consumes less than 2GB of memory. If the server memory is small, you can only open 25 php-cgi processes, so that the total amount of memory consumed by php-cgi is 500M.

The above data is from the Nginx 0.8.x + PHP 5.2.13 (FastCGI) build 10 times times more than Apache Web Server (6th edition)

What is php-cgi

PHP-CGI is PHP's own fastcgi manager

Php-cgi of the poor

1, php-cgi change php.ini configuration need to restart php-cgi to let the new Php-ini take effect, can not smooth restart

2, directly kill the php-cgi process, PHP can not run. (PHP-FPM and spawn-fcgi do not have this problem, the daemon will smooth the new child process from the newly generated.) ）

What is PHP-FPM

PHP-FPM is a PHP fastcgi manager that is only for PHP and can be downloaded in http://php-fpm.org/download.

PHP-FPM is actually a patch of PHP source code designed to integrate FASTCGI process management into a PHP package. It must be patch into your PHP source code and can be used after compiling and installing PHP.

Relative SPAWN-FCGI,PHP-FPM in the CPU and memory control are better, and the former is easy to crash, must be monitored with crontab, and PHP-FPM does not have this annoyance.

PHP5.3.3 has integrated php-fpm, no longer a third-party package. PHP-FPM provides a better way to manage the PHP process, can effectively control the memory and process, can be smooth overloaded PHP configuration, more than spawn-fcgi have a bit more, so by the official PHP included. The PHP-FPM can be turned on with the –ENABLE-FPM parameter when the./configure.

What is spawn-fcgi

SPAWN-FCGI is a general-purpose fastcgi Management Server, it is a part of LIGHTTPD, many people use lighttpd spawn-fcgi for fastcgi mode management work, but there are many shortcomings. And the php-fpm of how much to alleviate some of the problems, but PHP-FPM has a drawback is to recompile, which for some already running environment may have a small risk (refer), in PHP 5.3.3 can be directly used php-fpm.

SPAWN-FCGI has now become a single project, more stable, but also to many Web site configuration to facilitate. There are a number of sites to match it with Nginx to solve dynamic Web pages.

The newest lighttpd also does not contain this piece (Http://www.lighttpd.net/search?q=Spawn-FCGI), but it can be found in previous versions. Included in the lighttpd-1.4.15 version (http://www.lighttpd.net/download/lighttpd-1.4.15.tar.gz)

Currently spawn-fcgi is http://redmine.lighttpd.net/projects/spawn-fcgi, the latest version is http://www.lighttpd.net/download/ Spawn-fcgi-1.6.3.tar.gz

Note: The latest spawn-fcgi can search the Lighttpd.net website for "spawn-fcgi" to find the latest version of its release address

php-fpm and spawn-cgi comparison test

The PHP-FPM is very convenient to use, the configuration is in the Php-fpm.ini file, and the start, restart can be done from the PHP/SBIN/PHP-FPM. More convenient is to modify the php.ini can be directly used php-fpm reload loading, without killing the process can be completed php.ini modified loading
The results show that using PHP-FPM can make PHP a little more performance-boosting. PHP-FPM controlled process CPU recovery is slow, memory allocation is very uniform.

SPAWN-FCGI-controlled processes CPU drops quickly, while memory allocations are not evenly spaced. There are many processes that do not seem to be allocated, while others occupy very high. This may be due to uneven process assignment. This also leads to a decrease in overall response speed. The rational distribution of php-fpm leads to the reference of the overall response and the average of the task.

What are CGI, FastCGI, php-cgi, PHP-FPM, spawn-fcgi?