Differences and uses between WSGI, CGI, FastCGI, and mod_python in regards to Python?

Question

I'm just wondering what the differences and advantages are for the different CGI's out there. Which one would be best for python scripts, and how would I tell the script what to use?

Solution 1

A part answer to your question, including scgi.

• What's the difference between scgi and wsgi?
• Is there a speed difference between WSGI and FCGI?
• How Python web frameworks, WSGI and CGI fit together

CGI vs FCGI

Lazy and not writing it on my own. From the wikipedia: http://en.wikipedia.org/wiki/FastCGI

Instead of creating a new process for each request, FastCGI uses persistent processes to handle such requests. Multiple processes can configured, increasing stability and scalability. Each individual FastCGI process can handle many requests over its lifetime, thereby avoiding the overhead of per-request process creation and termination

Solution 2

There's also a good background reader on CGI, WSGI and other options, in the form of an official python HOWTO: http://docs.python.org/2/howto/webservers.html

Solution 3

In a project like Django, you can use a WSGI (Web Server Gateway Interface) server from the Flup module.

A WSGI server wraps a back-end process using one or more protocols:

• FastCGI (calling a server process)
• SCGI (Simple Common Gateway Interface - a simpler FastCGI)
• AJP (Apache JServ Protocol - a Java FastCGI)
• mod_python (runs pre-loaded code per request - uses lots of RAM)
• CGI (Common Gateway Interface, starts a process per request - slow)

Solution 4

• FastCGI is a kind of CGI which is long-live, which will always be running.
• With FastCGI, it'll take less time.
• Because of multi-processes, FastCGI will cost more memory than CGI.

In Detail Diff between FastCGI vs CGI

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Comments

[Parker]

Is mod_wsgi faster? My current server uses CGI, what reasons are there to switch?

[Koroviev]

Possible duplicate: stackoverflow.com/questions/219110/…

[user1066101]

We can't tell you if mod_wsgi will be faster in your environment. You have to actually measure them in your environment with your constraints and your applications and your configuration.

[anatoly techtonik]

mod_wsgi is Apache only. Is it still the most popular in 2012?

[xorcus]

There is a FastCGI stdio library (marcos) that let you make a single program capable of running both as CGI and as FastCGI app: fastcgi.com/devkit/doc/fastcgi-prog-guide/ap_guide.htm

[user345602]

Question about FastCGI: How it handle simultaneous connections with one process when PHP itself is blocking language ? What if I have something "sleep(100)" . Wont it block the process for the other users ? Thanks

[GiriB]

This is a great resource for beginners.

[lesnik]

Looks like the url is obsolete. But this one works: docs.python.org/2/howto/webservers.html