net/http: TestServerKeepAlivesEnabled_h2 test flakes

[mvdan]

--- FAIL: TestServerKeepAlivesEnabled_h2 (0.07s)
	clientserver_test.go:50: Get https://127.0.0.1:40070: write tcp 127.0.0.1:35196->127.0.0.1:40070: write: broken pipe

Seen here: https://storage.googleapis.com/go-build-log/55ca0192/linux-amd64_45ee111b.log

Similar to #18701, but not the same - that one only happens on Windows, and the error is different.

[bradfitz]

Also:

https://build.golang.org/log/1ed9b50cf1215a0e96f1420bef13396568ed57ac

ok  	net	55.406s
1 second passes in backend, proxygone= false
--- FAIL: TestServerKeepAlivesEnabled_h2 (4.34s)
	serve_test.go:5467: test server has active conns
FAIL
FAIL	net/http	33.092s
2017/12/01 01:00:27 Failed: exit status 1

/cc @tombergan

[bradfitz]

@tombergan, this test got slow (2 seconds) and flaky starting at your a8def0b (for "http2: always delay closing the connection after sending GOAWAY").

Can you take this one?

Before:

bradfitz@gdev:~/go/src/net/http$ git reset --hard a8def0bbbccb0e856e96ec35b0ebd68e1783042c^
(and make.bash)
bradfitz@gdev:~/go/src/net/http$ go test -v -run=TestServerKeepAlivesEnabled_h -count=5
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (0.01s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (0.01s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (0.01s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (0.01s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (0.01s)
PASS    
ok      net/http        0.060s

After:

bradfitz@gdev:~/go/src/net/http$ git reset --hard a8def0bbbccb0e856e96ec35b0ebd68e1783042c
HEAD is now at a8def0b net/http: update bundled http2
bradfitz@gdev:~/go/src/net/http$ go test -v -run=TestServerKeepAlivesEnabled_h -count=5
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.02s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (2.03s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (2.02s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (2.02s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (2.03s)
=== RUN   TestServerKeepAlivesEnabled_h1
--- PASS: TestServerKeepAlivesEnabled_h1 (0.00s)
=== RUN   TestServerKeepAlivesEnabled_h2
--- PASS: TestServerKeepAlivesEnabled_h2 (2.02s)
PASS                    
ok      net/http        10.160s

[bradfitz]

@tombergan, nevermind, I remembered how you fixed the other test and did it here too.

[gopherbot]

Change https://golang.org/cl/81576 mentions this issue: net/http: speed up and deflake TestServerKeepAlivesEnabled_h2