client.go

package main

import (
	"log"
	"math/rand"
	"net"
	"runtime"
	"strconv"
	"syscall"
)

var dns = make(chan interface{}, 10000)
var unix = make(chan interface{}, 20000)

func test() {
	for {
		dns <- nil
		go func() {
			for {
				hn := strconv.FormatInt(int64(rand.Int31()), 10) + ".com"
				net.ResolveIPAddr("ip", hn)
				log.Print(hn)
			}
			<-dns
		}()
	}
}

func main() {

	runtime.GOMAXPROCS(8)
	if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &syscall.Rlimit{Max: 50000, Cur: 50000}); err != nil {
		log.Printf("failed setting syscall.RLIMIT_NOFILE to 50K, the bug will not be reproducible")
		return
	}

	go test()

	for {
		unix <- nil
		go func() {
			var err error
			var conn net.Conn

			for {
				conn, err = net.Dial("unix", "/tmp/test.sock")

				if err != nil {
					log.Print(err)
				} else {
					break
				}
			}

			if err != nil {
				return
			}

			conn.Write([]byte("foo\n"))
			conn.Write([]byte("bar\n"))
			conn.Write([]byte("baz\n"))
			conn.Close()
			<-unix
		}()
	}
}

server.go

package main

import (
	"io"
	"log"
	"net"
	"os"
)

const sockpath = "/tmp/test.sock"

func main() {

	os.Remove(sockpath)

	ln, err := net.Listen("unix", sockpath)

	if err != nil {
		panic(err)
	}

	for {

		conn, err := ln.Accept()
		if err != nil {
			log.Print(err)
			continue
		}

		buf := make([]byte, 12)
		n, err := io.ReadFull(conn, buf)

		if n != len(buf) {
			log.Printf("has read only %v bytes: %s\n", n, string(buf))
		}

		if string(buf) != "foo\nbar\nbaz\n" {
			log.Printf("has read something wrong: %s\n", string(buf))
		}

		conn.Close()
	}
}