帮忙看看为什么会死锁

基于你的代码修改，首先fmt.Println(<-endChan)会造成deadlock，然后select中的break并不能跳出外层for循环，代码如下：

package main

import (
    "bufio"
    "fmt"
    "io"
    "log"
    "os"
    "strconv"
    "time"
)

func readData(bfRd io.Reader, dataChan chan []byte, endChan chan error) {
    buf := make([]byte, 100)
    for {
        n, err := bfRd.Read(buf)
        if err != nil {
            endChan <- err
            return
        }
        fmt.Printf("read data %s size \n", strconv.Itoa(n))
        dataChan <- buf
    }
}

func main() {
    file, err := os.Open("client.go")
    if err != nil {
        log.Fatalln(err)
    }
    var data []byte
    bfRd := bufio.NewReader(file)
    var dataChan = make(chan []byte)
    var endChan = make(chan error)
    go readData(bfRd, dataChan, endChan)
L:
    for {
        select {
        case err := <-endChan:
            fmt.Println(err)
            break L
        case <-dataChan:
            data = append(data, <-dataChan...)
        case <-time.After(time.Second):
            fmt.Println("timeout")
            break L
        default:
            fmt.Println("channel cannot use")
        }
    }
    fmt.Println(string(data))
}

你上面的代码真的不忍看，漏洞百出，我修改过的，你看下，地址：https://play.golang.org/p/-qntkhCVVtA

package main

import (
    "bufio"
    "fmt"
    "io"
    "log"
    "os"
    "strconv"
    "time"
)

func readData(bfRd io.Reader, dataChan chan []byte, endChan chan error) {
    buf := make([]byte, 100)
    for {
        n, err := bfRd.Read(buf)
        if err != nil {
            endChan <- err
            return
        }
        fmt.Printf("read data %s size \n", strconv.Itoa(n))
        dataChan <- buf[:n]
    }
}

func main() {
    file, err := os.Open("/Users/abin/data/e/dev1/server/src/lab/lab1.go")
    if err != nil {
        log.Fatalln(err)
    }
    var data []byte
    bfRd := bufio.NewReader(file)
    var dataChan = make(chan []byte)
    var endChan = make(chan error)
    go readData(bfRd, dataChan, endChan)
    var d []byte
L:
    for {
        select {
        case err := <-endChan:
            fmt.Println(err)
            break L
        case d = <-dataChan:
            data = append(data, d...)
        case <-time.After(time.Second):
            fmt.Println("timeout")
            break L
        default:
            fmt.Println("channel cannot use")
        }
    }
    fmt.Println(string(data))
}