[Twisted-Python] Reactor hangs on second call to reactor.run

[Ed Manlove]

I am creating a Plone product which uses Twisted's nntp module to fetch 
newsgroup postings and display them within my Plone site.  Within a 
Plone template I call the Plone External Method, XXXnewsreader. The 
first time I view the page containing this external method it runs fine 
but the second time it hangs.

I've run the python debugger and it appears to be running an infinite 
loop within the function mainloop within the class PosixReactorBase.

Can anyone share some ideas about what I may be doing wrong here or why 
the reactor appears to be stuck in the mainlop func?  Thanks for any 
assistance in advance.

I am running under Windows XP using Twisted 2.5.0 and using Plone 2.1.3, 
Zope 2.8.7-final, python 2.3.5.

Ed



def XXXnewsreader(self):
     print self.REQUEST.form
     n = XXXNewsGroup('localhost','local.programming')
     n.run_XXXNewsGroup()
     return n.result


class XXXDefaultNewsGroupPageProcedure(nntp.NNTPClient):

     def connectionMade(self):
         #pdb.set_trace()
         nntp.NNTPClient.connectionMade(self)
         self.fetchGroup(self.factory.newsgroup)

     def gotGroup(self, groupInfo):
         estNumMsgs, first, last, groupName, type, status = groupInfo
         first = int(first)
         last = int(last)
         start = max(first, last-self.factory.headerCount);
         self.headersToFetch = range(start, last+1)
         self.headerCount = len(self.headersToFetch)
         self.fetchNextHeader()

     def fetchNextHeader(self):
         if self.headersToFetch:
             nextHeaderId = self.headersToFetch.pop(0)
             print "Fetching header %i of %i..." % (
                 self.headerCount-len(self.headersToFetch),
                 self.headerCount),
             self.fetchHead(nextHeaderId)
         else:
             self.quit()
             self.factory.deferred.callback(self.factory.headers)

     def gotHead(self, header):
         print "OK"
         self.factory.handleHeader(header)
         self.fetchNextHeader()

     def getHeadFailed(self, errorMessage):
         print errorMessage
         self.fetchNextHeader()

     def getGroupFailed(self, errorMessage):
         self.factory.defered.errback(Exception(errorMessage))
         self.quit()
         self.transport.loseConnection()

     def connectionLost(self, error):
         if not self.factory.deferred.called:
             self.factory.deferred.errback(error)

class XXXDefaultNewsGroupPageFactory(protocol.ClientFactory):
     protocol = XXXDefaultNewsGroupPageProcedure

     def __init__(self, deferred, newsgroup, headerCount=5):
         self.newsgroup = newsgroup
         self.headerCount = headerCount
         self.headers = []
         self.deferred = deferred  # defer.Deferred()

     def handleHeader(self, headerData):
         header = HeaderParser(Message).parsestr(headerData, True);
         self.headers.append(header)
         temail = parseaddr(header['from'])
         realName, emailAddress = temail

class XXXNewsGroup:

     def __init__(self, nntpserver, newsgroup):
         self.server = nntpserver
         self.newsgroup = newsgroup
         self.deferred = defer.Deferred()
         self.result = ''

     def run_XXXNewsGroup(self):
         #pdb.set_trace()
         factory = XXXDefaultNewsGroupPageFactory(self.deferred, 
self.newsgroup)
         self.deferred.addCallback(
             self._toHTMLsuccess).addErrback(
             self.handleError)
         self.deferred.addCallback(
             self.handleSuccess).addErrback(
             self.handleError)
         reactor.connectTCP(self.server, 119, factory)
         reactor.run(installSignalHandlers=0)
         return self.result

     def _toHTMLsuccess(self, results):
         str = '<ul>\n'

         for header in results:
             temail = parseaddr(header['from'])
             realName, emailAddress = temail

             str += '  <ul>\n'
             str += '    <li>%s</li>\n' % header['subject']
             str += '    <li>%s</li>\n' % realName
             str += '    <li>%s</li>\n' % header['date']
             str += '  </ul>\n'

         str += '</ul>\n'
         return str

     def handleSuccess(self, result):
         self.result = result
         pdb.set_trace()
         reactor.stop()

     def handleError(self, error):
         self.result = error.getErrorMessage()
         print self.result
         reactor.stop()