x/net/http2: Transport leaks goroutines (awaitRequestCancel)

[g7r]

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

go version go1.10 darwin/amd64
go version go1.10.1 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/sz/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/sz/src/gohome"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.10/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.10/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/9h/x_80x8ln3_g038_zj_t9tszw0000gn/T/go-build456657465=/tmp/go-build -gno-record-gcc-switches -fno-common"

GOARCH="amd64"
GOBIN=""
GOCACHE="/home/sz/.cache/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/sz/go"
GORACE=""
GOROOT="/home/sz/goroot/1.10.1/go"
GOTMPDIR=""
GOTOOLDIR="/home/sz/goroot/1.10.1/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build220690427=/tmp/go-build -gno-record-gcc-switches"

What did you do?

HTTP2 client leaks goroutines when the following conditions are met:

1. http.Client has Timeout set
2. TLS connections are forcibly dropped
3. MaxConcurrentStreams is reasonably low

Test program that reproduces the issue: https://gist.github.com/g7r/3044f20a47e5d41630d9a2cdc5c24918

What did you expect to see?

It is expected to see steady number of goroutines.

What did you see instead?

Number of goroutines grows infinitely.
Leaked goroutine stacktraces are:

#	0x1243f5f	net/http.http2awaitRequestCancel+0x13f				/usr/local/Cellar/go/1.10/libexec/src/net/http/h2_bundle.go:6780
#	0x127ca8b	net/http.(*http2ClientConn).awaitOpenSlotForRequest.func1+0x3b	/usr/local/Cellar/go/1.10/libexec/src/net/http/h2_bundle.go:7519

[bradfitz]

@tombergan, that code was added in golang/net@1c05540f (https://go-review.googlesource.com/53250)

Could you take a look?

[meirf]

(I think I found the bug. Now I'm working on a test. Should have CL in next couple days.)

[gopherbot]

Change https://golang.org/cl/108415 mentions this issue: http2: terminate await request cancel goroutine on conn close

[gopherbot]

Change https://golang.org/cl/111655 mentions this issue: net/http: update bundled http2

[gopherbot]

Change https://golang.org/cl/111876 mentions this issue: vendor, net/http: update x/net for httplex to httpguts merge