Description:Enable restrictions on use of STDOUT.
Syntax:WSGIRestrictStdout On|Off
Default:WSGIRestrictStdout On
Context:server config

A well behaved Python WSGI application should never attempt to write any data directly to sys.stdout or use the print statement without directing it to an alternate file object. This is because ways of hosting WSGI applications such as CGI use standard output as the mechanism for sending the content of a response back to the web server. If a WSGI application were to directly write to sys.stdout it could interfere with the operation of the WSGI adapter and result in corruption of the output stream.

In the interests of promoting portability of WSGI applications, mod_wsgi restricts access to sys.stdout and will raise an exception if an attempt is made to use sys.stdout explicitly.

The only time that one might want to remove this restriction is purely out of convencience of being able to use the print statement during debugging of an application, or if some third party module or WSGI application was errornously using print when it shouldn’t. If restrictions on using sys.stdout are removed, any data written to it will instead be sent through to sys.stderr and will appear in the Apache error log file.