Re: asynchronous comunication, wxPython and threads.
- From: Zunbeltz Izaola <zunbeltz@xxxxxxxxx>
- Date: Wed, 22 Jun 2005 10:10:38 +0200
On Tue, 21 Jun 2005 11:07:35 -0400, Peter Hansen wrote:
>
> Please clarify: what does this mean? "Sending a socket" is not a usual
> way to describe TCP communications. Do you mean your program _opens_ a
> socket (like a phone connection) and _sends_ some data, then waits for
> data to be received from the other end? Or are you (as it almost
> sounds) opening and closing sockets repeatedly for each part of the
> conversation?
>
Sorry for the lack of clarity. I opened the socket once (i don't know if
itit is important to open inside or outside the comunication thread). And
them send "packages" and wait for data.
>
> I think you are using the term "socket" where you should be using
> "packet". A socket is the virtual connection created by TCP. A packet
> is either a single blob of data sent by the TCP code in the operating
> system, or perhaps a single chunk of your own data.
>
Thanks for the vocabulary correction.
> If you are using a single TCP socket to send multiple packets, and you
> are talking about those packets being sent out of order, it's very
> unlikely and there must be another explanation. TCP _is_ reliable, and
> you will not get data out of order unless you do something to screw
> things up, for example by creating a race condition by doing
> multithreaded code incorrectly.
>
I think this is the case (see the post of Toby). I didn't try it out but I
think the problem is that i *do* comunication in both threads.
>
> Some people advise that, but there's really nothing *wrong* with doing
> this in a second thread, and in fact I do similar things all the time
> with no ill effects. While async frameworks _can_ make this easier,
> they could also make it harder (at least for a while) as you adjust your
> brain to the new approach. Furthermore, at least in the case of
> wxPython and Twisted (on Windows) there can be problems integrating the
> two loops. I don't believe the latest Twisted claims to have fully
> solved the problems involved yet, so you might still be required to have
> a second thread for the TCP stuff.
>
Yes, i have read that there is problems yet.
>
> I use a non-blocking socket and select() calls in my thread, and
> communicate with the GUI thread using appropriate Queue objects and
> calls to PostEvent() (or CallAfter()) on the wx side of things. It's
> pretty straightforward, so if you post a small piece of your application
> which reproduces the problem it shouldn't be hard for someone here to
> help you fix it.
>
Thanks. First i would check if the problem is what Toby says.
>
> No more so than using threads, unless your problem is caused by the
> threads themselves (as I suggested above) in which case it might be
> easier to just fix the problem.
>
> -Peter
Thank you very much
Zunbeltz
.
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