[Python-Dev] threadsafe patch for asynchat

Josiah Carlson jcarlson at uci.edu
Wed Feb 8 01:57:15 CET 2006

Guido van Rossum <guido at python.org> wrote:
> IMO asynchat and asyncore are braindead. The should really be removed
> from the standard library. The code is 10 years old and represents at
> least 10-year-old thinking about how to do this. The amount of hackery
> in Zope related to asyncore was outrageous -- basically most of
> asyncore's guts were replaced with more advanced Zope code, but the
> API was maintained for compatibility reasons. A nightmare.

I'm going to go ahead and disagree with Guido on this one.  Before
removing asyncore (and asynchat) from the standard library, I believe
that there would necessarily need to be a viable replacement already
in place. The SocketServer module and its derivatives are wholly
unscalable for server-oriented applications once you get past a few
dozen threads (where properly designed asyncore derivatives will do
quite well all the way to your platform file handle limit).

Every once and a while I hear about people pushing for Twisted to be
included with Python, but at 2 megs for the base bz2 package, it seems a
little...hefty.  I'm not aware of any other community-accepted package
for asynchronous socket clients and servers, but I'm always looking.

Now, don't get me wrong, writing servers and clients using asyncore or
asynchat can be a beast, but it does get one into the callback/reactor
method of programming, which seems to have invaded other parts of Python
and 3rd party libraries (xml.sax, tk, Twisted, wxPython, ...).

Back to the topic that Guido was really complaining about: Zope +
asyncore.  I don't doubt that getting Zope to play nicely with asyncore
was difficult, but it begs the questions: what would have been done if
asyncore didn't exist, and why wasn't that done instead of trying to
play nicely with asyncore?

 - Josiah

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