Comment 1 by xuxinhua1984:

If the above is not bug, the following should be bug：（if the above fixed by my code,
the following code runs ok.)
http://play.golang.org/p/JCQV4uN8GJ
I write data 3 times, but I read 4 times.
This issue can fixed by above code, otherwise, this code is also can fix it:
io/pipe.go, line 42:
change the code 
        for {
        if p.rerr != nil {
            return 0, ErrClosedPipe
        }
        if p.data != nil {
            break
        }
        if p.werr != nil {
            return 0, p.werr
        }
        p.rwait.Wait()
    }
to 
       for {
        if p.rerr != nil {
            return 0, ErrClosedPipe
        }
                if p.werr != nil {
            return 0, p.werr
        }
        if p.data != nil {
            break
        }
        p.rwait.Wait()
    }

Comment 2:

I'm having trouble reproducing the problem you reported. I'm also having trouble
figuring out if it is an issue. Please consider this slightly simplified example
http://play.golang.org/p/Vhh0PoiEKq

Status changed to WaitingForReply.

Comment 3:

ping

Comment 4:

http://play.golang.org/p/bXlyS33kEE
package main
import (
    "fmt"
    "io"
)
func main() {
    r, w := io.Pipe()
    go func() {
        w.Write([]byte("hello"))
        w.Close()
        w.Write([]byte("world"))
    }()
    buf := make([]byte, 100)
    for i := 0; i < 3; i++ {
        n, err := r.Read(buf)
        fmt.Printf("%q %v\n", buf[:n], err)
    }
}
"hello" <nil>
"world" <nil>
"" EOF

Labels changed: added priority-later, go1.2, removed priority-triage.

Status changed to Accepted.

Comment 5:

This issue was closed by revision 4be9385.

Status changed to Fixed.