[bug] SetReadDeadLine did not work

[weiyixuan]

go version: 1.12.8
platform: win10、macos、android

When I used wsc.SetReadDeadLine, I found that the ReadMessage exited before the timeout period reached, resulting in high-frequency execution of the loop and eventually crash.

`

for {

	wsc.SetReadDeadLine(time.Now().Add(500 * time.Millisecond))

	if _, buf, err = wsc.ReadMessage(); err != nil {

		log.Error(err)

		continue

	}

	...

}

`

[elithrar]

What is the full program? What are you reading off the socket? The deadline won’t be reached if ReadMessage returns faster than the deadline.

[weiyixuan]

Windows 10 Professional 64 bit：10.0.17763.774

func main(){
	var err error

	header := http.Header{}
        // header setting

	dialer := &websocket.Dialer{
		TLSClientConfig: &tls.Config{
			InsecureSkipVerify: true,
		},
		HandshakeTimeout: 6 * time.Second,
	}

	var wsc *websocket.Conn
	if wsc, _, err = dialer.Dial(`wss://x.x.x.x:443/...`, header); err != nil {
		log.Error(err)
		return
	}
	for {
		wsc.SetReadDeadline(time.Now().Add(time.Second))
		_, _, err = wsc.ReadMessage()
		fmt.Println(err)
	}
}

result：
……
read tcp 172.20.32.62:3733->x.x.x.x:443: i/o timeout
……
read tcp 172.20.32.62:3733->x.x.x.x:443: i/o timeout
read tcp 172.20.32.62:3733->x.x.x.x:443: i/o timeout
read tcp 172.20.32.62:3733->x.x.x.x:443: i/o timeout
read tcp 172.20.32.62:3733->x.x.x.x:443: i/o timeout
panic: repeated read on failed websocket connection

[nhooyr]

You need to return from the loop if err is non nil.

[weiyixuan]

You're right. But I'm curious as to why the timeout didn't work. The above log was printed in a flash.

[nhooyr]

Well you set a deadline of 1s. Also, once a deadline is hit, the connection is done, see #474

[weiyixuan]

Ok, got it. ୧(๑•̀◡•́๑)૭