Simon Giesecke

But it may still be useful, e.g. to allow to enable rr chaos mode selectively.

I just noticed that there already is an implementation using WSAWaitForMultipleEvents, but it is only used when there are sockets from multiple address families in a poller. It also seems...

@Kentzo since you added this code with 538e5d47421f45d88a8b3b005ed9ee4026623a7b, can you say something about whether you tested this? It is not tested on appveyor at the moment, unfortunately.

@Kentzo since you added this code with 538e5d47421f45d88a8b3b005ed9ee4026623a7b, can you say something about whether you tested this? It is not tested on appveyor at the moment, unfortunately.

Ok I now had another look and I think I understand how it works. I think a different implementation might do without select completely and outperform this. What is suboptimal...

WSAEVENTS is but the wsa_eventst ctor calls WSACreateEvent which is expensive: https://github.com/zeromq/libzmq/commit/538e5d47421f45d88a8b3b005ed9ee4026623a7b#diff-872ce26b9fb528e0ec0abd474883ca8aR457

I will benchmark/profile it, the expensive WSACreateEvent turned up by that. What is also expensive is get_fd_family, getsockname in particular. loop, set_poll* and reset_poll* are among the most frequently called...

I have added a cache in 37914d1be23b89f7bd747d02ee5a56a18a12d7c3, it is not LRU, but just randomly overwrites entries, this could still be improved. I attempted an implementation wsa_event_select_t in https://github.com/sigiesec/libzmq/tree/add-wsa-eventselect-poller, but I...

What might be even better in terms of performance/scalability were to use I/O completion ports, which is what NetMQ does: http://somdoron.com/2014/11/netmq-iocp/ However, I think this requires more extensive changes to...

An even faster way appears to be the Winsock Registered I/O extensions, which are supported from Windows 8.1 (RIOCloseCompletionQueue, RIOCreateCompletionQueue, RIOCreateRequestQueue, RIODequeueCompletion, RIODeregisterBuffer, RIONotify, RIOReceive, RIOReceiveEx, RIORegisterBuffer, RIOResizeCompletionQueue, RIOResizeRequestQueue, RIOSend,...