io tee problem

tee.go

package main

import (
	"flag"
	"fmt"
	"io"
	"time"
)

func newReader() io.Reader {
	pr, pw := io.Pipe()
	go func() {
		for {
			s := fmt.Sprint(time.Now().UnixNano())
			pw.Write([]byte(s))
			time.Sleep(time.Second)
		}
	}()
	return pr
}

func read(source string, r io.Reader, notRead bool) {
	if notRead {
		time.Sleep(time.Hour)
	}
	buff := make([]byte, 1e3)
	for {
		n, err := r.Read(buff)
		if err != nil {
			break
		}
		fmt.Printf("read from [%s]: %s\n", source, buff[:n])
	}
}

func main() {

	mode := flag.Int("mode", 1, "1=read all; 2=not read teeReader; 3=not read pipeReader")
	flag.Parse()

	oriReader := newReader()

	pipeReader, pw := io.Pipe()
	teeReader := io.TeeReader(oriReader, pw)

	switch *mode {
	case 1:
		fmt.Println("read all (mode 1)")
		go read("teeReader", teeReader, false)
		go read("pipeReader", pipeReader, false)

	case 2:
		fmt.Println("not read teeReader (mode 2)")
		// change the order will solve it but no outputs neither
		read("pipeReader", pipeReader, false)
		go read("teeReader", teeReader, true)

	case 3:
		fmt.Println("not read pipeReader (mode 3)")
		// change the order will solve it but no outputs neither
		read("teeReader", teeReader, false)
		go read("pipeReader", pipeReader, true)
	}

	c := make(chan bool)
	<-c
}

➜  io.tee go run main.go -mode 3
not read pipeReader (mode 3)
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [select]:
io.(*pipe).Write(0xc420092140, 0xc42009e000, 0x13, 0x3e8, 0x0, 0x0, 0x0)
	/usr/local/go/src/io/pipe.go:87 +0x1e3
io.(*PipeWriter).Write(0xc42000c040, 0xc42009e000, 0x13, 0x3e8, 0x13, 0x0, 0x0)
	/usr/local/go/src/io/pipe.go:153 +0x4c
io.(*teeReader).Read(0xc42000a060, 0xc42009e000, 0x3e8, 0x3e8, 0x3e8, 0x3e8, 0x1d)
	/usr/local/go/src/io/io.go:535 +0xb1
main.read(0x10d3a57, 0x9, 0x10e60e0, 0xc42000a060, 0x0)
	/Users/shaun.fu/test/go/io.tee/main.go:28 +0x183
main.main()
	/Users/shaun.fu/test/go/io.tee/main.go:59 +0x2f0

goroutine 5 [select]:
io.(*pipe).Write(0xc4200920f0, 0xc420018260, 0x13, 0x20, 0x0, 0x0, 0x0)
	/usr/local/go/src/io/pipe.go:87 +0x1e3
io.(*PipeWriter).Write(0xc42000c030, 0xc420018260, 0x13, 0x20, 0x13, 0x20, 0x0)
	/usr/local/go/src/io/pipe.go:153 +0x4c
main.newReader.func1(0xc42000c030)
	/Users/shaun.fu/test/go/io.tee/main.go:15 +0xfb
created by main.newReader
	/Users/shaun.fu/test/go/io.tee/main.go:12 +0x149
exit status 2

➜  io.tee go run main.go -mode 2
not read teeReader (mode 2)
fatal error: all goroutines are asleep - deadlock!

goroutine 1 [select]:
io.(*pipe).Read(0xc420092140, 0xc42009c000, 0x3e8, 0x3e8, 0x10afc40, 0x1, 0xc42009c000)
	/usr/local/go/src/io/pipe.go:50 +0x115
io.(*PipeReader).Read(0xc42000c038, 0xc42009c000, 0x3e8, 0x3e8, 0x3e8, 0x3e8, 0x1c)
	/usr/local/go/src/io/pipe.go:127 +0x4c
main.read(0x10d3c0d, 0xa, 0x10e60a0, 0xc42000c038, 0x0)
	/Users/shaun.fu/test/go/io.tee/main.go:28 +0x183
main.main()
	/Users/shaun.fu/test/go/io.tee/main.go:55 +0x3bd

goroutine 5 [select]:
io.(*pipe).Write(0xc4200920f0, 0xc42009e040, 0x13, 0x20, 0x0, 0x0, 0x0)
	/usr/local/go/src/io/pipe.go:87 +0x1e3
io.(*PipeWriter).Write(0xc42000c030, 0xc42009e040, 0x13, 0x20, 0x13, 0x20, 0x0)
	/usr/local/go/src/io/pipe.go:153 +0x4c
main.newReader.func1(0xc42000c030)
	/Users/shaun.fu/test/go/io.tee/main.go:15 +0xfb
created by main.newReader
	/Users/shaun.fu/test/go/io.tee/main.go:12 +0x149
exit status 2