说明：

Source And Sink

package pipeline

import (
    "encoding/binary"
    "fmt"
    "io"
    "math/rand"
    "sort"
    "time"
)

var startTime time.Time

func Init() {
    startTime = time.Now()
}

func ArraySource(a ...int) chan int {
    out := make(chan int)
    go func() {
        for _, v := range a {
            out <- v
        }
        close(out)
    }()
    return out
}

func InMemSort(in <-chan int) <-chan int {
    out := make(chan int, 1024)
    go func() {
        //Read into memo
        var a []int
        for v := range in {
            a = append(a, v)
        }
        fmt.Println("Read done:", time.Now().Sub(startTime))
        //
        sort.Ints(a)
        fmt.Println("InMemSort done:", time.Now().Sub(startTime))
        for _, v := range a {
            out <- v
        }
        close(out)
    }()
    return out
}

func Merge(in1, in2 <-chan int) <-chan int {
    out := make(chan int, 1024)
    go func() {
        v1, ok1 := <-in1
        v2, ok2 := <-in2
        for ok1 && ok2 {
            if v1 <= v2 {
                out <- v1
                v1, ok1 = <-in1
            } else {
                out <- v2
                v2, ok2 = <-in2
            }
        }
        if !ok1 {
            for ok2 {
                out <- v2
                v2, ok2 = <-in2
            }
        }
        if !ok2 {
            for ok1 {
                out <- v1
                v1, ok1 = <-in1
            }
        }
        close(out)
        fmt.Println("Merge done:", time.Now().Sub(startTime))
    }()
    return out
}

func ReaderSource(reader io.Reader, chunkSize int) <-chan int {
    out := make(chan int, 1024)
    go func() {
        buffer := make([]byte, 8)
        bytesRead := 0
        for {
            n, err := reader.Read(buffer)
            bytesRead += n
            if n > 0 {
                v := int(binary.BigEndian.Uint64(buffer))
                out <- v
            }
            if err != nil || (chunkSize != -1 && bytesRead >= chunkSize) {
                break
            }
        }
        close(out)
    }()
    return out
}

func WriteSink(writer io.Writer, in <-chan int) {
    for v := range in {
        buffer := make([]byte, 8)
        binary.BigEndian.PutUint64(buffer, uint64(v))
        writer.Write(buffer)
    }
}

func RandomSource(count int) <-chan int {
    out := make(chan int, 1024)
    go func() {
        for i := 0; i < count; i++ {
            out <- rand.Int()
        }
        close(out)
    }()
    return out
}

func MergeN(inputs ...<-chan int) <-chan int {
    if len(inputs) == 1 {
        return inputs[0]
    }
    m := len(inputs) / 2
    //merge inputs[0...m) and inputs[m...end)
    return Merge(
        MergeN(inputs[:m]...),
        MergeN(inputs[m:]...), )
}

testfile文件生成

生成测试文件（small.in/large.in）,对应的小文件和大文件

package main

import (
    "bufio"
    "fmt"
    "os"
    "pipeline"
)

//生成小的测试文件
//const FILE_NAME = "small.in"
//const N = 64

//生成大的测试文件
const FILE_NAME = "large.in"
const N = 1000000

func main() {
    file, e := os.Create(FILE_NAME)
    if e != nil {
        panic(e)
    }
    defer file.Close()

    p := pipeline.RandomSource(N)
    writer := bufio.NewWriter(file)
    pipeline.WriteSink(writer, p)
    writer.Flush()

    file, e = os.Open(FILE_NAME)
    if e != nil {
        panic(e)
    }
    defer file.Close()

    p = pipeline.ReaderSource(file, -1)

    count := 0
    for v := range p {
        count++
        if count < 100 {
            fmt.Println(v)
        }
    }
}

//测试内存的二分排序
func main0() {
    p := pipeline.Merge(
        pipeline.InMemSort(pipeline.ArraySource(8, 2, 3, 0, 1)),
        pipeline.InMemSort(pipeline.ArraySource(9, 7)),
    )
    for v := range p {
        fmt.Println(v)
    }
}

利用网络排序

package pipeline

import (
    "bufio"
    "net"
)

func NetworkSink(addr string, in <-chan int) {
    listen, err := net.Listen("tcp", addr)
    if err != nil {
        panic(err)
    }

    go func() {
        defer listen.Close()
        conn, err := listen.Accept()
        if err != nil {
            panic(err)
        }
        defer conn.Close()
        writer := bufio.NewWriter(conn)
        defer writer.Flush()
        WriteSink(writer, in)
    }()
}

func NetworkSource(addr string) <-chan int {
    out := make(chan int)
    go func() {
        conn, err := net.Dial("tcp", addr)
        if err != nil {
            panic(err)
        }

        defer conn.Close()
        r := ReaderSource(conn, -1)
        for v := range r {
            out <- v
        }
        close(out)
    }()
    return out
}

测试主方法

package main

import (
    "bufio"
    "fmt"
    "os"
    "pipeline"
    "strconv"
)

func main2() {
    p := createNetworkPipeline("large.in", 8000000, 4)

    writeToFile(p, "large-networkpipeline.out")
    printFile("large-networkpipeline.out")
}

func main1() {
    p := createPipeline("large.in", 8000000 , 4)
    writeToFile(p, "large-pipeline.out")
    printFile("large-pipeline.out")
}

func printFile(filename string) {
    file, err := os.Open(filename)
    if err != nil {
        panic(err)
    }
    defer file.Close()

    p := pipeline.ReaderSource(file, -1)
    count := 0
    for v := range p {
        if count < 100 {
            fmt.Println(v)
            count ++
        }
    }
}

func writeToFile(p <-chan int, filename string) {
    file, err := os.Create(filename)
    if err != nil {
        panic(err)
    }
    defer file.Close()

    writer := bufio.NewWriter(file)
    defer writer.Flush()

    pipeline.WriteSink(writer, p)
}

func createPipeline(filename string, filesize, chunkCount int) <-chan int {
    chunkSize := filesize / chunkCount
    pipeline.Init()
    var sortResults []<-chan int
    for i := 0; i < chunkCount; i++ {
        file, err := os.Open(filename)
        if err != nil {
            panic(err)
        }
        file.Seek(int64(i*chunkSize), 0)

        source := pipeline.ReaderSource(
            bufio.NewReader(file), chunkSize)
        sortResults = append(sortResults, pipeline.InMemSort(source))
    }
    return pipeline.MergeN(sortResults...)
}

func createNetworkPipeline(filename string, filesize, chunkCount int) <-chan int {
    chunkSize := filesize / chunkCount
    pipeline.Init()
    var sortAddr []string
    for i := 0; i < chunkCount; i++ {
        file, err := os.Open(filename)
        if err != nil {
            panic(err)
        }
        file.Seek(int64(i*chunkSize), 0)

        source := pipeline.ReaderSource(
            bufio.NewReader(file), chunkSize)
        addr := ":" + strconv.Itoa(7000+i)
        pipeline.NetworkSink(addr, pipeline.InMemSort(source))
        sortAddr = append(sortAddr, addr)
    }

    var sortResults []<-chan int
    for _, addr := range sortAddr {
        sortResults = append(sortResults, pipeline.NetworkSource(addr))
    }
    return pipeline.MergeN(sortResults...)
}