thread safe SMTP module

[Aahz]

In article <mailman.4644.1172997256.32031.python-list at python.org>,
Gordon Messmer  <yinyang at eburg.com> wrote:
>Aahz wrote:
>> 
>> That doesn't make any sense.  Blocking I/O generally releases the GIL,
>> which is the whole reason Python doesn't totally suck for threading.
>
>Nevertheless, among the caveats listed at 
>http://docs.python.org/lib/module-thread.html is:
>
>"Not all built-in functions that may block waiting for I/O allow other 
>threads to run. (The most popular ones (time.sleep(), file.read(), 
>select.select()) work as expected.)"

That's why I said "generally".

>> There may be other thread problems, but I doubt that you have correctly
>> analyzed their source.
>
>I subclassed smtplib.SMTP and replaced only the lines of code that had 
>to do with blocking IO (connect, send and receive operations). 
>Beforehand, python would occasionally lock up. Having made those 
>changes, python stopped locking up.  I think the problem was pretty well 
>apparent.  I can't pin it down to which one of those three operations 
>was at fault, and it may be that only one was.  However, when I use 
>non-blocking IO, the application works.  When I used smtplib.SMTP, it 
>didn't.
>
>I'm open to other explanations.

Assuming you have correctly tracked down the problem area, I would call
that a thread bug in Python.  But my experience is that you simply have
run into a problem with the socket.  I would suggest that using
socket.setdefaulttimeout() would work just as well.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"I disrespectfully agree."  --SJM