Switch default transport to sockets

[natemcmaster]

Currently, it is our goal by 2.1.0 to make sockets the default transport. We made the switch in early builds of 2.1.0 but reverted that for preview1 (#2220) due to performance issues.

Motivations:

• broad platform support. Wherever managed sockets are supported, Kestrel should work. Doesn't require recompiling libuv to bring up a new OS.
• source-build. (https://github.com/dotnet/source-build). In current form, Kestrel packages can't be produced in a source-build environment
• ecosystem. Helps to drive improvement to the .NET sockets implementation, which benefits anyone else using managed sockets.

/cc @halter73 @davidfowl @muratg

[Suchiman]

@halter73 shouldn't the announcement prefer Microsoft.AspNetCore.App over Microsoft.AspNetCore.All? EDIT: Oh looks like i can't read properly, so App won't contain Libuv but All does.

[halter73]

@Suchiman Your edit is correct. That's the main thing that makes the change breaking.

[ondravondra]

Do the managed sockets have similar performance compared to libuv?

[NinoFloris]

@ondravondra yes that was the prerequisite for the switch and why preview1 still ships with libuv. I think it might even be.a little faster already

[davidfowl]

@halter73 this is done, can you close this issue?

[nickalbrecht]

Just a heads up, the announcement has the tag 2.0.0-preview2, not 2.1.0-preview2

[natemcmaster]

@nickalbrecht thanks for spotting that. I updated the milestone on the announcement.

[ghost]

Do the managed sockets have similar performance compared to libuv?

@ondravondra yes that was the prerequisite for the switch and why preview1 still ships with libuv. I think it might even be.a little faster already

Couple of months ago, it was indicated that performance regressed when switching to sockets #2220. Are there any before/after performance measurements to bring about concreteness to the mix?

[Suchiman]

@kasper3
There is http://aka.ms/aspnet/benchmarks
If you navigate to page 1 with the pager at the bottom, there's a graph that shows Socket I/O by over a million RPS ahead of Libuv.
If you go to page 2 it looks differently so i don't really understand how to read them.

EDIT: Ah i think i see my mistake. Sockets PlainText Platform is a bit faster than LibUv PlainText Platform and both are ~1.5 million RPS faster than Kestrel LibUv PlainText which is a bit faster than Sockets PlainText. Interesting that only the Platform Level Benchmark of Sockets beats LibUv.