golang.org/x/crypto/ssh: goroutine leak

[mei-rune]

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

$ go version
go version go1.16.3 windows/amd64

Does this issue reproduce with the latest release?

yes

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

go env Output

$ go env

What did you do?

d:\developing\go\meijing\src\cn\com\hengwei_private>go env
set GO111MODULE=
set GOARCH=amd64
set GOBIN=
set GOCACHE=d:\developing\go-build
set GOENV=C:\Users\runne\AppData\Roaming\go\env
set GOEXE=.exe
set GOFLAGS=
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOINSECURE=
set GOMODCACHE=d:\developing\go\meijing\pkg\mod
set GONOPROXY=
set GONOSUMDB=
set GOOS=windows
set GOPATH=d:\developing\go\meijing;d:\developing\go\meijing\tpt_vendor;d:\developing\go\meijing..\aah;
set GOPRIVATE=
set GOPROXY=https://goproxy.cn,https://goproxy.io,direct
set GOROOT=d:\tools\go
set GOSUMDB=sum.golang.org
set GOTMPDIR=
set GOTOOLDIR=d:\tools\go\pkg\tool\windows_amd64
set GOVCS=
set GOVERSION=go1.16.3
set GCCGO=gccgo
set AR=ar
set CC=gcc
set CXX=g++
set CGO_ENABLED=1
set GOMOD=d:\developing\go\meijing\src\cn\com\hengwei_private\go.mod
set CGO_CFLAGS=-g -O2
set CGO_CPPFLAGS=
set CGO_CXXFLAGS=-g -O2
set CGO_FFLAGS=-g -O2
set CGO_LDFLAGS=-g -O2
set PKG_CONFIG=pkg-config
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0 -fdebug-prefix-map=C:\Users\runne\AppData\Local\Temp\go-build40258698=/tmp/go-build -gno-record-gcc-switches

What did you expect to see?

goroutine profile: total 2892
450 @ 0x43ecfa 0x406c7a 0x4068eb 0xb4b794 0x474b01
#	0xb4b793	golang.org/x/crypto/ssh.(*Client).handleGlobalRequests+0x73	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/client.go:138

450 @ 0x43ecfa 0x406c7a 0x4068eb 0xb4b819 0x474b01
#	0xb4b818	golang.org/x/crypto/ssh.(*Client).handleChannelOpens+0x58	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/client.go:147

450 @ 0x43ecfa 0x406c7a 0x4068eb 0xb513f5 0xb6975e 0xb695bc 0x474b01
#	0xb513f4	golang.org/x/crypto/ssh.(*handshakeTransport).readPacket+0x54	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/handshake.go:187
#	0xb6975d	golang.org/x/crypto/ssh.(*mux).onePacket+0x3d			d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/mux.go:215
#	0xb695bb	golang.org/x/crypto/ssh.(*mux).loop+0x3b			d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/mux.go:190

450 @ 0x43ecfa 0x44fd48 0xb51945 0x474b01
#	0xb51944	golang.org/x/crypto/ssh.(*handshakeTransport).kexLoop+0xe4	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/handshake.go:268

450 @ 0x43ecfa 0x46f997 0x46f96d 0x47f05f 0xb68b8b 0xb735da 0x474b01
#	0x46f96c	sync.runtime_notifyListWait+0xec		d:/tools/go_amd64/src/runtime/sema.go:513
#	0x47f05e	sync.(*Cond).Wait+0x9e				d:/tools/go_amd64/src/sync/cond.go:56
#	0xb68b8a	golang.org/x/crypto/ssh.(*mux).Wait+0x8a	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/mux.go:110
#	0xb735d9	golang.org/x/crypto/ssh.NewClient.func1+0x39	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/client.go:62

448 @ 0x43ecfa 0x434b25 0x46dde5 0x502dac 0x504333 0x505556 0x565fb6 0x579818 0x68ccb8 0x48326e 0xb467a7 0xb46757 0xb7148f 0xb713a5 0xb51f97 0xb514d4 0x474b01
#	0x46dde4	internal/poll.runtime_pollWait+0x64					d:/tools/go_amd64/src/runtime/netpoll.go:222
#	0x502dab	internal/poll.(*pollDesc).wait+0x4b					d:/tools/go_amd64/src/internal/poll/fd_poll_runtime.go:87
#	0x504332	internal/poll.execIO+0x112						d:/tools/go_amd64/src/internal/poll/fd_windows.go:175
#	0x505555	internal/poll.(*FD).Read+0x2f5						d:/tools/go_amd64/src/internal/poll/fd_windows.go:441
#	0x565fb5	net.(*netFD).Read+0x55							d:/tools/go_amd64/src/net/fd_posix.go:55
#	0x579817	net.(*conn).Read+0x97							d:/tools/go_amd64/src/net/net.go:183
#	0x68ccb7	bufio.(*Reader).Read+0x237						d:/tools/go_amd64/src/bufio/bufio.go:227
#	0x48326d	io.ReadAtLeast+0x8d							d:/tools/go_amd64/src/io/io.go:328
#	0xb467a6	io.ReadFull+0x86							d:/tools/go_amd64/src/io/io.go:347
#	0xb46756	golang.org/x/crypto/ssh.(*streamPacketCipher).readCipherPacket+0x36	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/cipher.go:153
#	0xb7148e	golang.org/x/crypto/ssh.(*connectionState).readPacket+0x6e		d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/transport.go:130
#	0xb713a4	golang.org/x/crypto/ssh.(*transport).readPacket+0x44			d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/transport.go:114
#	0xb51f96	golang.org/x/crypto/ssh.(*handshakeTransport).readOnePacket+0x56	d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/handshake.go:374
#	0xb514d3	golang.org/x/crypto/ssh.(*handshakeTransport).readLoop+0x53		d:/developing/go/meijing/tpt_vendor/src/golang.org/x/crypto/ssh/handshake.go:197

What did you see instead?

goroutine no leak

My code is

	conn, err := ssh.Dial("tcp", client.host, config)
	if err != nil {
		return errors.New("connect failed, " + err.Error())
        }
	defer conn.Close()
	
	for {
                .........
               bs, err := executeRequest(conn, request)
                if nil != err {
		      return errors.New("execute failed, " + err.Error())
               }
               ...
        }


...
func executeRequest()  ([]byte, error) {
	sess, e := conn.NewSession()
	if nil != e {
		return nil, e
	}
	defer sess.Close()

	var b safeWriter
	sess.Stdout = &b
	sess.Stderr = &b
	e = sess.Start(cmd)
	if e != nil {
		return nil, e
	}

	c := make(chan error, 1)
	go func() {
		c <- sess.Wait()
	}()

	timer := time.NewTimer(command_timeout)
	select {
	case e = <-c:
		timer.Stop()
		return b.b.Bytes(), e
	case <-timer.C:
		e = sess.Signal(ssh.SIGINT)
		if e != nil {
			timer.Reset(10 * time.Second)
			select {
			case e = <-c:
				timer.Stop()
			case <-timer.C:
				sess.Signal(ssh.SIGKILL)
			}
			log.Println("execute '" + cmd + "' is timeout")
			e = errors.NewRuntimeError(sampling.TimeoutError.ErrorCode(), "execute '"+cmd+"' is timeout")
		}
		return b.b.Bytes(), e
	}
       ........
}

[YenchangChan]

I have the same problem as you, how do you solve it？