On 2012-10-29, at 3:32 PM, Andrew Svetlov
On Mon, Oct 29, 2012 at 9:10 PM, Yury Selivanov
On 2012-10-29, at 2:02 PM, Andrew Svetlov
Pollster has to support any object as file descriptor. The use case is ZeroMQ sockets: they are implemented at user level and socket is just some opaque structure wrapped by Python object. ZeroMQ has own poll function to process zmq sockets as well as regular sockets/pipes/files.
Well, you can use epoll/select/kqueue or whatever else with ZMQ sockets. Just get the underlying file descriptor with 'getsockopt', as described here: http://api.zeromq.org/master:zmq-getsockopt#toc20
Well, will take a look. I used zmq poll only. It works for reading only, not for writing, right? As I know you use proactor pattern. Can reactor has some problems with this approach? May embedded 0MQ poll be more effective via some internal optimizations?
It's officially documented and supported approach. We haven't seen any problem with it so far. It works both for reading and writing, however, 99.9% EAGAIN errors occur on reading. When you 'send', it just stores your data in an internal buffer and sends it itself. When you 'read', well, if there is no data in buffers you get EAGAIN. As for the performance -- I haven't tested 'zmq.poll' vs (let's say) epoll, but I doubt there is any significant difference. And if I would want to write a benchmark, I'd first compare pure blocking ZMQ sockets vs non-blocking ZMQ sockets with ZMQ.poll, as ZMQ uses threads heavily, and probably, blocking threads-driven IO is faster then non-blocking with polling (when FDs count is relatively small), no matter whether you use zmq.poll or epoll/etc. - Yury