async_resolve endpoint overload is blocking on Windows

[sweatybridge]

I ran into this problem while trying to do multiple reverse lookups simultaneously. Each lookup is using a unique instance of endpoint::resolver. However, the resolution did not happen asynchronously. A similar problem has been posted on the user list back in 2014: https://lists.boost.org/boost-users/2014/12/83445.php

May I suggest that we update the documentation so that software engineers are aware of such issues in the future?
http://www.boost.org/doc/libs/1_64_0/doc/html/boost_asio/reference/ip__basic_resolver/async_resolve/overload2.html

[vinniefalco]

But the documentation already states that asynchronous name resolutions on Windows are simulated using a per-io-service thread that the asio implementation provides. Is that insufficient?

[sweatybridge]

That would indeed be sufficient. But I was not able to find that statement anywhere. Are we possibly looking at different documentation pages?

[vinniefalco]

See Windows NT, 2000, XP, 2003, Vista, 7 and 8

http://www.boost.org/doc/libs/1_65_1/doc/html/boost_asio/overview/implementation.html#boost_asio.overview.implementation.windows_nt__2000__xp__2003__vista__7_and_8

• An additional thread per io_service is used to emulate asynchronous host resolution. This thread is created on the first call to either ip::tcp::resolver::async_resolve() or ip::udp::resolver::async_resolve().

Seems like you have not yet committed the entirety of the Boost.Asio documentation to memory :)

[sweatybridge]

:) that and also I've not tried enough permutations of search terms.

[vinniefalco]

Check out Boost.Beast, HTTP and WebSocket using Boost.Asio:
https://github.com/boostorg/beast