[mod_python] Re: post request and the minimalistic handler

Daniel Nogradi nogradi at gmail.com
Mon Feb 20 19:16:46 EST 2006

> There are still some problems with the FieldStorage class and large files.
> If you want to upload a
> large file, you MUST use a make_file callback to the FieldStorage
> constructor and NEVER call
> form["file"] for that field or your apache process will load the whole file
> into RAM.
> In other words:
> - Does it work with small (e.g. 10k) files?
> - Look at apache's memory usage.

There are two things I don't understand here. First, if you don't give
a file callback function to FieldStorage it uses the default one,
which is creating a temporary file and that is where a file from a
posted form data will get written. So why would apache load that into
memory? The corresponding part of util.py is:

       # is this a file?
       if disp_options.has_key("filename"):
           if file_callback and callable(file_callback):
               file = file_callback(disp_options["filename"])
               file = self.make_file()


        def make_file(self):
              return tempfile.TemporaryFile("w+b")

The second thing is that in my example FieldStorage can not possibly
be a source of any problems as the whole request handler is only:

from mod_python import apache

def handler( req ):
     req.content_type = "text/html"
     req.write( "hello" )
     return apache.OK

so FieldStorage is not even instantiated. My understanding is that
with such a handler the body of a POST request is simply lost and is
neither read into memory nor anywhere else.

Another thought in this direction: I plan to write an inputfilter for
large file uploads in order to avoid FieldStorage all together. Has
anyone done such a thing?

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