Cherrypy hanging on form post

Question

I'm currently trying to remove a legacy python framework (webware 0.8.1) and layer cherrypy 3.1.2 on top of it. Instead of converting all the webware pages to cherrypy pages, I'm merely processing it through webware and passing it to cherrypy like so.

def default(self, url, *suburl, **kwarg):    
  ...snip...
  strmout = DispatcherIO()
  request = HTTPRequest(local_req)
  transaction = self.create_transaction(request)
  response = self.create_response(transaction, strmout)
  transaction.setServlet(servlet)
  transaction.awake()
  transaction.respond()
  return str(strmout)

This works fine for any page that doesn't include a POST. But with any page including a post such as the login, cherrypy would hang at:

request = HTTPRequest(local_req)

This calls FieldStorage which will call the constructor for the parant cgi.FieldStorage. This is where it finally hangs.

However, if I were to press ctrl-c on the terminal, it would continue processing and then terminate after the page successfully loads. So with the login page, I would click "login", it would hang, I will then press ctrl-c on the terminal, it will log me in and then shutdown cherrypy.

I found that if I used cherrypy.engine.start instead of quickstart it would not initiate any signal handlers. What would happen in this case would result in something similar as to the previous behaviour however cherrypy would continue running.

What could be causing this problem? I would really appreciate any help. Cheers.

• HTTPRequest
• FieldStorage

Answer 1

I don't really have experience with Webware, but based on the appearance of your code, Webware is trying to use cgi.FieldStorage to retrieve your field variables, but FieldStorage can't get the length, or gets the length incorrectly (probably because whatever Webware does to get the Content-Length header doesn't work in your CherryPy WSGI environment - the default implementation retrieves the HTTP_CONTENT_LENGTH environment variable, and Webware probably does something similarly hacky), so it's reading and then it hangs. I had a similar problem often when working with CGI.

The best solution is to not use cgi.FieldStorage. If the HTTPRequest object in question is coming from Webware, my recommendation is to either port your site to CherryPy completely (or some other Web framework), or just use Webware in its native environment. Hacking something up might be possible, but WSGI is very different from Webware's native environment of its own application server.