[Tutor] sockets, files, threads
Marilyn Davis
marilyn at deliberate.com
Mon Jan 17 04:59:14 CET 2005
On Sat, 15 Jan 2005, Danny Yoo wrote:
>
>
> > I have only wrapped my lock around file-descriptor creations. Should I
> > wrap it around closings too? Or the whole open -> close transaction?
> > It sounds like error-prone work to do the latter. What am I missing?
>
> Hi Marilyn,
>
> Can you send a link to the source code to the Tutor list? I'm getting the
> feeling that there's might be a design problem. Just adding locks
> whenever something doesn't work is not a sustainable way to write a
> multithreaded application.
>
> We have to see why your file descriptors being are being shared between
> threads. Is there a reason why you need to share them as global
> resources?
No. And I don't. They are often attributes of instantiations of
classes; or they come and go quickly.
Thank you for offering to look at the code. Start at:
http://www.maildance.com/python/doorman/README
Then, the daemon that creates the threads is:
http://www.maildance.com/python/doorman/py_daemon.py
I'm testing using calls to:
http://www.maildance.com/python/doorman/route_mail.py
http://www.maildance.com/python/doorman/doorman.py
Other modules that open and close file descriptors from there are:
http://www.maildance.com/python/doorman/db.py
http://www.maildance.com/python/doorman/doorman_log.py
http://www.maildance.com/python/doorman/exim.py
http://www.maildance.com/python/doorman/move.py
I'll be grateful for any improvements you suggest. But, I do know
that some modules aren't well-documented, or are hardly documented at
all yet. And db.py seems like a mess to me. But I'm not ready to
straighten it up yet.
But the most important one, py_daemon.py, I hope is very readable.
Still though, I should confess, I am feeling a bit dismal about the
thread situation, especially since searching around for info on
critical code. The examples I found, before I gave up, were all
trivial. Also, there is this article:
http://linuxgazette.net/107/pai.html
Which says that the performance is almost the same with threads as
with single-threading. Boo.
So suddenly, I have no idea why I'm down this road. We have a huge
performance savings from setting up a daemon that reads a socket.
But, unless something changes our minds soon, I'll rip threading out
of our code.
Still though, I am a teacher too, and a student. So any thoughts you
have about our code will be treated like the pearls they are.
Thank you again.
Marilyn
>
>
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