net/http: TestLinuxSendfile is flaky

[carl-mastrangelo]

What version of Go are you using (go version)?

Fri Nov 04 05:09:56$ go version
go version go1.7.3 linux/amd64

What operating system and processor architecture are you using (go env)?

Fri Nov 04 05:09:54$ go env
GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GORACE=""
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build238588156=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

What did you do?

./all.bash

What did you expect to see?

Successful build

What did you see instead?

ok  	net	1.795s
--- FAIL: TestLinuxSendfile (0.04s)
	fs_test.go:1123: no sendfile system call found in:
		[pid 122885] sendfile(6, 8, NULL, 22 <unfinished ...>
		[pid 122894] +++ exited with 0 +++
		[pid 122893] +++ exited with 0 +++
		[pid 122892] +++ exited with 0 +++
		[pid 122891] +++ exited with 0 +++
		+++ exited with 0 +++
FAIL
FAIL	net/http	2.699s

It looks like the regexp to match sendfile is missing a matcher for "". Considering that this test appears to check just that sendfile is called, it should be enough that the call is started (as printed above).

[gopherbot]

CL https://golang.org/cl/32759 mentions this issue.