[zeromq-dev] pyzmq select/_poll implementation problem

Brian Granger ellisonbg at gmail.com
Mon Apr 12 20:13:00 CEST 2010


This is a bug.  I fixed some problems in poll, but forgot to update
select.  Could you file a ticket on the github page for pyzmq?

select should work like you are expecting and it is probably a trivial
fix.  I will try to get to this soon, but if you want to have a stab
and fixing
it, go for it.



On Mon, Apr 12, 2010 at 10:58 AM, Laurens Van Houtven <lvh at laurensvh.be> wrote:
> Hey,
> I'm running into trouble using zmq.select instead of select.select. The end
> goal is to get something based on select (specifically, twisted) to be able
> to read from ZMQ sockets as well as plain old file descriptors. In a naive
> attempt to get that to work, I tried this:
> http://bpaste.net/show/5455/
> So, I started investigating. Consider the following Python function, in
> _zmq.pyx: http://paste.pocoo.org/show/201079/
> The sockets list, used as an argument to _poll, is clearly an iterable of
> things that can live in {r,w,x}list, so, either:
>     - zmq.Socket
>     - int (an fd)
>     - object implementing fileno returning an int
> However, _poll says in its docstring that its sockets argument should be a
> list of tuples of (socket, flags). Look at its implementation
> (http://paste.pocoo.org/show/201080/, sorry, no syntax highlighting -- I
> couldn't find a pastebin that does that for Cython), specifically lines 22
> and 23. It appears that _poll isn't lying in its docstring, so it appears
> that select isn't feeding it what it wants.
> This results in the following problem if I try to use select-using code, but
> select.select replaced with zmq.select:
> http://bpaste.net/show/5455/
> The problem is that in the two aforementioned lines, _zmq.pyx tries to do
> sockets[i][0], but sockets[i] is just an integer (specifically, a fd)
> What am I missing? The obvious fix of appending (s, flags) instead just
> seems a tad *too* obvious. Is zmq.select even supposed to work like this?
> tia
> lvh
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Brian E. Granger, Ph.D.
Assistant Professor of Physics
Cal Poly State University, San Luis Obispo
bgranger at calpoly.edu
ellisonbg at gmail.com

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