[hunchentoot-devel] Problems with file uploads and mod_lisp

[Edi Weitz]

Hi!

I just realized that Hunchentoot in its current form has problems with
file uploads if it's used behind mod_lisp.  I could reproduce this
with Apache 2 as well as Apache 1 and with LispWorks (but only on
Linux, not on Windows) as well as with SBCL.

To try this yourself, start the demo that comes with Hunchentoot and
upload a couple of pictures (I used JPEGs) in the file upload section.
Click on the uploaded pictures and view them.

Symptoms that I see:

  - files are sometimes uploaded only partly

  - you see an Apache error message after an upload is finished (which
    usually means that mod_lisp can't talk to Lisp)

  - server gets completely unresponsive after some time

It seems this is not deterministic, though.  I've had situations where
I uploaded the same picture a couple of times, and sometimes the whole
file reached the server, sometimes only a part of it.  One of the
reasons for this that I could observe is that when rfc2388.lisp reads
characters from the content stream, READ-CHAR sometimes returns NIL
although the whole file hasn't been transferred yet (i.e. there should
be more input available).

I'm writing this because I haven't found the reason for this behaviour
yet and I'll probably be too busy in the next days to do something
about it.  Obviously, I'd be happy if someone else would debug this
and find a solution.  Meanwhile, maybe you shouldn't use Hunchentoot
with mod_lisp for production servers.  The stand-alone version doesn't
seem to be affected, though.

Cheers,
Edi.