在立即運行服務器之前釋放埠

我想go在linux基于系統的系統上運行一個服務器，它發生在我發現同一個埠忙于另一個應用程式的情況下，所以我想終止該埠上正在運行的行程，并運行我的服務器，所以我寫了下面代碼：

func main() {

    host := "127.0.0.1"
    port := "8070"
    server := http.Server{
        Addr: "127.0.0.1:8070",
    }

    http.Handle("/www/", http.StripPrefix("/www/", http.FileServer(http.Dir("./www"))))

    ln, err := net.Listen("tcp", ":" port)

    if err != nil {
        fmt.Fprintf(os.Stderr, "Can't listen on port %q: %s \n", port, err)
        // kill the running process at this port
        _, err := exec.Command("fuser", "-k", "8070/tcp").Output()

        if err != nil {
            fmt.Printf("Failed to kill process at Port %q\n", port)
        } else {
            fmt.Printf("TCP Port %q is available\n", port)
            server.ListenAndServe()
        }

    } else {
        ln.Close()
        server.ListenAndServe()
    }
}

我能夠得到回應TCP Port 8070 is availablewhihc 意味著有另一個正在運行的行程并且它已被殺死，但是我的應用程式直接關閉，而沒有在已經關閉的同一埠上運行我的服務器！

hajsf@AIS-DM-YOUSEF-L:~/myapp$ go run myapp
Can't listen on port "8070": listen tcp :8070: bind: address already in use 
TCP Port "8070" is available
hajsf@AIS-DM-YOUSEF-L:~/myapp$ 

在原始終端中（我得到的 app0 的舊實體；

hajsf@AIS-DM-YOUSEF-L:~/myapp$ go run myapp
signal: killed
hajsf@AIS-DM-YOUSEF-L:~/myapp$ 

uj5u.com熱心網友回復：

在 CentOS 7 上運行良好，但在 Ubuntu 服務器上也有同樣的問題。@MoiioM 的回答很好。但是如果另一個應用程式不是 golang 應用程式本身，這是另一種方法：在套接字上設定一個 SO_REUSEADDR 標志

package main

import (
    "context"
    "fmt"
    "net"
    "net/http"
    "os"
    "os/exec"
    "syscall"

    "golang.org/x/sys/unix"
)

func reusePort(network, address string, conn syscall.RawConn) error {
    return conn.Control(func(descriptor uintptr) {
        syscall.SetsockoptInt(int(descriptor), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
    })
}

func main() {

    port := "8070"
    server := http.Server{}

    http.Handle("/www/", http.StripPrefix("/www/", http.FileServer(http.Dir("./www"))))

    ln, err := net.Listen("tcp", ":" port)

    if err != nil {
        fmt.Fprintf(os.Stderr, "Can't listen on port %q: %s \n", port, err)
        // kill the running process at this port
        _, err := exec.Command("fuser", "-k", "8070/tcp").Output()

        if err != nil {
            fmt.Printf("Failed to kill process at Port %q\n", port)
        } else {
            fmt.Printf("TCP Port %q is available\n", port)
            config := &net.ListenConfig{Control: reusePort}
            listener, err := config.Listen(context.Background(), "tcp", ":" port)
            if err != nil {
                panic(err)
            }
            if err := server.Serve(listener); err != nil {
                panic(err)
            }
        }

    } else {
        if err := server.Serve(ln); err != nil {
            panic(err)
        }
    }
}

uj5u.com熱心網友回復：

正如您在回應中看到的如何終止在 Linux 中的特定埠上運行的行程？

您的命令會_, err := exec.Command("fuser", "-k", "8070/tcp").Output()終止行程，但不會清除資源，即：埠偵聽。父行程被殺死后，埠進入 TIME_WAIT 狀態。

你需要等待一段時間你的作業系統/內核清理埠/套接字

更好的選擇是處理 kill sigintfuser并正常關閉

package main

import (
    "context"
    "fmt"
    "net"
    "net/http"
    "os"
    "os/exec"
    "os/signal"
    "time"
)

func runServer(host, port string) {
    server := http.Server{
        Addr: host   ":"   port,
    }
    http.Handle("/www/", http.StripPrefix("/www/", http.FileServer(http.Dir("./www"))))
    go func() {
        if err := server.ListenAndServe(); err != nil {
        }
    }()

    // Setting up signal capturing
    stop := make(chan os.Signal, 1)
    signal.Notify(stop, os.Interrupt)

    // Waiting for SIGINT (kill -2)
    <-stop

    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()
    if err := server.Shutdown(ctx); err != nil {
        // handle err
    }
}

func main() {

    host := "127.0.0.1"
    port := "8070"
    ln, err := net.Listen("tcp", host ":" port)

    if err != nil {
        fmt.Fprintf(os.Stderr, "Can't listen on port %q: %s \n", port, err)
        // kill the running process at this port
        cmd := exec.Command("fuser", "-k", "-2", "8070/tcp")
        fmt.Println("wait")
        err = cmd.Run()

        if err != nil {
            fmt.Printf("Failed to kill process at Port %q\n", port)
        } else {
            fmt.Printf("TCP Port %q is available\n", port)
            runServer(host, port)
        }

    } else {
        ln.Close()
        runServer(host, port)
    }
}

uj5u.com熱心網友回復：

我能夠解決它panic ... recover如下：

package main

import (
    "fmt"
    "net"
    "net/http"
    "onsen/resources"
    "onsen/routes"
    "os"
    "os/exec"
)

func main() {
    http.Handle("/webUI/", http.StripPrefix("/webUI/", http.FileServer(http.FS(resources.WebUI))))
    http.Handle("/www/", http.StripPrefix("/www/", http.FileServer(http.Dir("./www"))))

    for key, value := range routes.Urls() {
        http.HandleFunc(key, value)
    }
    runServer()
}
func runServer() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("Recovered in f", r)
            runServer()
        }
    }()

    host := "127.0.0.1"
    port := "8070"

    server := http.Server{
        Addr: fmt.Sprintf("%v:%v", host, port),
    }

    ln, err := net.Listen("tcp", ":" port)

    if err != nil {
        fmt.Fprintf(os.Stderr, "Can't listen on port %q: %s \n", port, err)
        // kill the running process at this port
        _, err := exec.Command("fuser", "-k", "8070/tcp").Output()

        if err != nil {
            panic(fmt.Sprintf("Failed to kill process at Port %q\n", port))
        } else {
            fmt.Printf("TCP Port %q is available\n", port)
            fmt.Println("server started...")
            if err := server.Serve(ln); err != nil {
                panic(err)
            }
        }
    } else {
        fmt.Println("server started...")
        if err := server.Serve(ln); err != nil {
            panic(err)
        }
    }
}

并得到如下輸出：

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