客户端无法将数据发送到Golang中的TCP服务器？

Question

我有一个TCP服务器和一个客户端，简单的TCP服务器将接收传入的数据并打印出来，而客户端将继续创建一个套接字连接并循环发送数据到TCP服务器。

我得到的信息是，如果一个TCP连接被正确地关闭了，这个过程应该会继续下去，不会发生任何崩溃。

但在从客户端接收到一定数量的数据到服务器之后,客户端会崩溃,并出现错误

total times data send: 16373

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x10d7594]

goroutine 1 [running]:
main.sendData()

/Users/apple/Desktop/Personal/umbrellaserver/src/tests/clinet.go:178 
+0xb4
main.main()

/Users/apple/Desktop/Personal/umbrellaserver/src/tests/clinet.go:170 
+0x2a
exit status 2

package main

import (
    "bufio"
    "fmt"
    "net"
    "sync"
)

var wg sync.WaitGroup
var count = 0
var timeX string = ""

var connQueue = make(chan string)

func main() {
    tcpListner := startTCPConnection()
    incomingTCPListener(tcpListner)
}

//startTCPConnection
func startTCPConnection() net.Listener {
    tcpListner, tcpConnectonError := net.Listen("tcp", "localhost:3000")
    if tcpConnectonError != nil {
        print(tcpConnectonError)
        return 
    }
    return tcpListner
}

//incomingTCPListener
func incomingTCPListener(tcpListner net.Listener) {

    for {
        incomingConnection, incomingConnectionError := tcpListner.Accept()
        if incomingConnectionError != nil {
            print(incomingConnectionError)
            return
        }
        wg.Add(1)
        go processIncomingRequest(incomingConnection)
        wg.Wait()
    }
}

//processIncomingRequest
func processIncomingRequest(connection net.Conn) {

    defer connection.Close()

    var scanner = bufio.NewScanner(connection)

    var blob = ""
    for scanner.Scan() {
        fmt.Println("sadd")
        text := scanner.Text()
        blob += text
    }
    print(blob)
    count++
    fmt.Println("totalCount", count)
    wg.Done()
}

package main

import (
    "fmt"
    "net"
)

var count = 0

func testJSON2() string {
    return `Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32. The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions from the 1914 translation by H. Rackham.`
}

func main() {
    for i := 0; i < 1000000; i++ {
        sendData()
    }

}

func sendData() {

    connection, connectionError := net.Dial("tcp", "localhost:3000")
    defer connection.Close()

    if connectionError != nil {
        fmt.Println(connectionError)
        return 
    }
    newmessage := testJSON2()
    connection.Write([]byte(newmessage + "\n"))
    count++
    fmt.Println(count)
}

有没有什么办法可以避免这次撞车，让它持续运行呢？我是新来的所以如果我犯了什么愚蠢的错误，我很抱歉。

Answer 1

首先，如果您想打印到stderr（即您的打印调用），我建议您使用fmt库

fmt.Fprintln(os.Stderr, "hello world")

原因：因为打印功能不能保证保留在该语言中。1

其次，通常使用err这样的名称来给错误命名，您不必拼写出TCPConnectionError这样的错误。

>> sysctl net.inet.ip.portrange.first net.inet.ip.portrange.last
net.inet.ip.portrange.first: 49152
net.inet.ip.portrange.last: 65535

最后,

如果希望避免端口耗尽导致的崩溃:
1。增加端口的临时范围
2。使用Docker，容器在它们自己的网络上，因此使用一组不同的端口，绕过有限的端口范围。
3。在客户端代码中引入一个报价器，以模拟每x秒/分钟一次的连接

package main

import (
    "fmt"
    "net"
    "time"
)

var count = 0

func testJSON2() string {
    return `Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32. The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions from the 1914 translation by H. Rackham.`
}

func main() {
    max := 1000

    timer1 := time.NewTicker(5 * time.Second)

    i := 0
    for range timer1.C {
        sendData()
        if i == max {
            timer1.Stop()
        }
        i++
    }
}

func sendData() {

    connection, connectionError := net.Dial("tcp", "localhost:3000")
    fmt.Println(connection.LocalAddr())

    if connectionError != nil {
        fmt.Println(connectionError)
        return
    }
    newmessage := testJSON2()
    connection.Write([]byte(newmessage + "\n"))
    count++
    fmt.Println(count)

    err := connection.Close()
    if err != nil {
        fmt.Println(err)
    }
}

引用
^1:https://tip.golang.org/pkg/builtin/#print
^2:MAC上临时端口的范围是什么？
^3:https://www.fromdual.com/humaug-amount-of-time-wait-connections