Golang在TCP上死锁。一段时间后写入

Question

I have this code for test. After some time all gorutines locks on carbonWriteBuf.Flush() without any error. Just stop. The more threads and the shorter the interval the faster the stop. If I kill received app (nc -l 127.0.0.1 2002 -k -m 1000) the Golang resets the connect and work again. But if the gorutine has already stopped, then there is no restart and any messages.

package main

import (
    "bufio"
    "flag"
    "fmt"
    "net"
    "time"
)

var (
    SERVER   string
    INTERVAL int
    THREADS  int
)

func main() {
    flag.StringVar(&SERVER, "s", "localhost:2002", "server address:port (Default: localhost:2002)")
    flag.IntVar(&INTERVAL, "i", 500, "send interval (Default: 500")
    flag.IntVar(&THREADS, "t", 100, "num of threads (Default: 100")
    flag.Parse()

    for i := 0; i < THREADS; i++ {
        go sender(i)
    }

    for {
    }
}

func sender(id int) {
    var carbonErr error
    var carbonWriteBuf *bufio.Writer
    var carbonConn net.Conn
    defer fmt.Println("End 1")
    x := 0

    i := 10
    isUp := true

    updater := time.NewTicker(time.Duration(INTERVAL*3) * time.Millisecond)
    go func() {
        defer fmt.Println("End 2")
        for range updater.C {
            if isUp {
                i++
            } else {
                i--
            }

            if i == 20 {
                isUp = false
            }

            if i == 0 {
                isUp = true
            }
            fmt.Println(x)
        }
    }()

    dataSender := time.NewTicker(time.Duration(INTERVAL) * time.Millisecond)
    func() {
        defer fmt.Println("End 3")
        for range dataSender.C {
            x++
            if carbonConn != nil {
                //carbonConn.SetWriteDeadline(time.Now().Add(time.Second * 3))
                if err := carbonConn.SetDeadline(time.Now().Add(time.Second * 3)); err != nil {
                    fmt.Println("Cannot set deadline", err)
                }
                if _, writeErr := carbonWriteBuf.WriteString(fmt.Sprintf("test.%d.value %d %d
", id, i, time.Now().Unix())); writeErr == nil {
                    fmt.Println("Buffered:", carbonWriteBuf.Buffered())

                    if flushErr := carbonWriteBuf.Flush(); flushErr == nil {
                        fmt.Println("Send", time.Now().Unix())
                    } else {
                        fmt.Printf("Cannot write data to carbon %s Error: %s
", carbonConn.RemoteAddr(), flushErr)
                        carbonConn = nil
                    }
                } else {
                    fmt.Println("Cannot write data to buffer:", writeErr)
                    carbonConn = nil
                }
            } else {
                if carbonConn, carbonErr = net.Dial("tcp", SERVER); carbonErr != nil {
                    carbonConn = nil
                    fmt.Println("Cannot connect to carbon:", carbonErr)
                } else {
                    defer carbonConn.Close()
                    carbonWriteBuf = bufio.NewWriterSize(carbonConn, 4096)
                    //carbonWriteBuf = bufio.NewWriter(carbonConn)
                    fmt.Println("Successfully connected to carbon:", carbonConn.RemoteAddr())
                }
            }
        }
    }()
}

Answer 1

Problem was in busy loop in main thread. Thanks JimB