[Twisted-Python] CONNECTION_LOST not an integer (docstring error?)
Michael McNeil Forbes
mforbes at physics.ubc.ca
Sat Oct 4 21:12:20 EDT 2008
On Oct 3, 2008, at 5:25 PM, glyph at divmod.com wrote:
>> I know that and am using callFromThread: The reason I am having
>> bad behavior is because the socket is backing up. Once I put in
>> the logic to throw out data, it works fine... but the lack of
>> reactor support concerns me somewhat.
> What do you mean by "backing up"? That doesn't really make sense.
> When a transport "backs up" in Twisted, it just allocates a larger
> and larger buffer to store the data that is queued to be sent.
I thought that the socket buffer was backing up, but now see that
write() does buffer. I incorrectly attributed some problems with
data arriving out of order and/or getting lost with this... I will
have to look deeper into what is causing these problems. I am using
a push producer now and the server seems to be sending things fine.
As far as I can tell, however, the receiver is sometimes getting the
data out of order when data comes in too fast on the client side. I
have to look into that and see what the cause is... maybe I am not
being careful enough with the threads.
(On the client side, I want the user to have full access to a python
interpreter with readline functionality etc. and the ability to plot
things with matplotlib using Tkinter. As far as I can see, I can't
get readline functionality with a manhole or similar interface
controlled by twisted, so again I have to run twisted in a separate
> And what is the "lack of reactor support" you're talking about?
Oh, the "lack of support" for writeSomeData by some reactors bothered
me and prompted me to use write;-)
>> I don't want the computation to stop, but think I could put an
>> intermediate "push producer" that stops by discarding the data.
> I don't *really* understand what you're trying to accomplish here;
> it soudns to me like you actually want a pull producer that just
> always sends the latest state in resumeProducing(), assuming it's
> always changing. Of course the "every 30 minutes" timeframe
> confuses that somewhat. However, using some kind of producer is
> definitely the way to go.
The point here is that there are two forms of usage: one is when the
computation is fast and the data is coming so fast that the client
will have to drop some of it. I agree that this should be more of a
pull producer, but the other form of usage is where the computation
takes about 30 minutes before new data is ready. This should be
implemented as a push producer.
>> Is there a simpler way to do this all with twisted without using
>> threads? (The main goal is having an extremely minimal set of
>> hooks for the people writing the computational code, and having
>> the computational code run as fast as possible.)
> You could use subprocesses. Valentino Volonghi is working on a
> convenient process-pool for use with Twisted: <https://
> launchpad.net/ampoule/>. I don't think that would actually help
> you that much though, since you'd still need to have application-
> specific buffering logic (it's a slightly unusual requirement to
> throw away intermediary state depending on the buffer saturation).
Thanks for the suggestions and help.
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