[Beast] Slow HTTP connect on Windows. Normal?

From: Dominique Devienne (ddevienne_at_[hidden])
Date: 2020-11-25 10:54:23

Hi. I'm writing a small interaction between:
1) a Boost.Beast-based HTTP server (based on http_server_async.cpp example)
2) a Boost.Beast-based HTTP client (based on http_client_sync.cpp example)

When I log the time it takes to resolve the server address and connect to
it, then issue my HTTP request, it takes over 1 second (Win10, VS2019,
C++17, Release, localhost for both client and server):

2020-11-25T09:46:37.473936 Prologue in 0.001s
2020-11-25T09:46:37.482470 Resolved in 0.008s
2020-11-25T09:46:38.506180 Connected in 1.023s
2020-11-25T09:46:38.509607 OK: Authenticated; in 0.003s

While the same on Linux (RH7.5) is just over 2ms:

2020-11-25T09:45:45.515926 Prologue in 0.000s
2020-11-25T09:45:45.517083 Resolved in 0.001s
2020-11-25T09:45:45.517550 Connected in 0.000s
2020-11-25T09:45:45.518010 OK: Authenticated; in 0.000s

That's a huge difference! Almost 500x...

And when I contact the same HTTP server on Windows, but from Chrome this
time,
it takes about 300ms, and if I hit reload rapidly, the time jumps around to
as low as 3ms,
and as high as 300ms (the same initial delay), with ~50ms and ~100ms in
between.
(I also see several different connections being established, for some
reason...)

I've seen similar differences between Windows and Linux connection times,
but with WebSocketPP-based client and server this time, also based on
Boost.ASIO.

Q1: Am I doing anything wrong? I.e. is this "normal" somehow?

Q2: How come Chrome, on Windows too, is 3x faster than ASIO-based clients,
with the same Beast-based server?

Given the high connect time on Windows, I thought I'd try to keep the
connection open on the client, and issue several send-request/read-response
pairs, using the Beast-based (sync) HTTP client, but only the first one
works correctly, the 2nd errors out with:

Error: An established connection was aborted by the software in your host
machine

I suspect it is a user-error, with the server closing the connection,
despite the Keep-Alive HTTP header being present server-side on the request.

Q3: Given the Beast HTTP examples I'm based off, would anyone have
suggestions on what changes are necessary to allow the client issuing
several (non-overlapping) requests to the server, on the same connection?
(since connecting is so expensive).

Q4: And for better performance, what about overlapping request/response
pairs, with HTTP pipelining. How to set that up on the client and server
with Beast?

Thanks for any help on this. --DD

PS: Great examples in Boost.Beast BTW. Thanks Vinnie.