英文:
Golang TCP client exits
问题
我正在尝试用Golang编写一个简单的客户端，但是一运行它就退出了。
package main
import (
"fmt"
"net"
"os"
"bufio"
"sync"
)
func main() {
conn, err := net.Dial("tcp", "localhost:8081")
if err != nil {
fmt.Println(err)
conn.Close()
}
fmt.Println("Got connection, type anything...new line sends and quit quits the session")
go sendRequest(conn)
}
func sendRequest(conn net.Conn) {
reader := bufio.NewReader(os.Stdin)
var wg sync.WaitGroup
for {
buff := make([]byte, 2048)
line, err := reader.ReadString('\n')
wg.Add(1)
if err != nil {
fmt.Println("Error while reading string from stdin",err)
conn.Close()
break
}
copy(buff[:], line)
nr, err := conn.Write(buff)
if err != nil {
fmt.Println("Error while writing from client to connection", err)
break
}
fmt.Println(" Wrote : ", nr)
wg.Done()
buff = buff[:0]
}
wg.Wait()
}
当我尝试运行它时，输出如下：
Got connection, type anything...new line sends and quit quits the session
Process finished with exit code 0
我期望这段代码会打开标准输入（终端）并等待输入文本，但它立即退出。我应该用其他代码替换它以从标准输入读取吗？
英文:
I am trying to write a simple client in Golang but it exits as soon as I run it,
package main
import (
"fmt"
"net"
"os"
"bufio"
"sync"
)
func main() {
conn, err := net.Dial("tcp", "localhost:8081")
if err != nil {
fmt.Println(err);
conn.Close();
}
fmt.Println("Got connection, type anything...new line sends and quit quits the session");
go sendRequest(conn)
}
func sendRequest(conn net.Conn) {
reader := bufio.NewReader(os.Stdin)
var wg sync.WaitGroup
for {
buff := make([]byte, 2048);
line, err := reader.ReadString('\n')
wg.Add(1);
if err != nil {
fmt.Println("Error while reading string from stdin",err)
conn.Close()
break;
}
copy(buff[:], line)
nr, err := conn.Write(buff)
if err != nil {
fmt.Println("Error while writing from client to connection", err);
break;
}
fmt.Println(" Wrote : ", nr);
wg.Done()
buff = buff[:0]
}
wg.Wait()
}
And when trying to run it, I get the following as output
Got connection, type anything...new line sends and quit quits the session
Process finished with exit code 0
I am expecting that the code would make stdin(terminal) open and wait for input text but it exits immediately. Should I be replacing the code with something else for reading from stdin
答案1
得分: 2
一个Go程序在main函数返回时退出。
简单的修复方法是直接调用sendRequest函数。在这个程序中不需要使用goroutine。
func main() {
conn, err := net.Dial("tcp", "localhost:8081")
if err != nil {
fmt.Println(err)
conn.Close()
}
fmt.Println("Got connection, type anything...new line sends and quit quits the session")
sendRequest(conn) // <-- 这一行去掉了go关键字
}
如果需要使用goroutine，可以使用sync.WaitGroup使main函数等待goroutine完成：
func main() {
conn, err := net.Dial("tcp", "localhost:8081")
if err != nil {
fmt.Println(err)
conn.Close()
}
var wg sync.WaitGroup
fmt.Println("Got connection, type anything...new line sends and quit quits the session")
wg.Add(1)
go sendRequest(&wg, conn)
wg.Wait()
}
func sendRequest(wg *sync.WaitGroup, conn net.Conn) {
defer wg.Done()
// 之前的代码
}
英文:
A Go program exits when the main function returns.
The simple fix is to call sendRequest directly. The goroutine is not needed in this program.
func main() {
conn, err := net.Dial("tcp", "localhost:8081")
if err != nil {
fmt.Println(err);
conn.Close();
}
fmt.Println("Got connection, type anything...new line sends and quit quits the session");
sendRequest(conn) // <-- go removed from this line.
}
If the goroutine is required, then use a sync.WaitGroup to make main wait for goroutines to complete:
func main() {
conn, err := net.Dial("tcp", "localhost:8081")
if err != nil {
fmt.Println(err);
conn.Close();
}
var wg sync.WaitGroup
fmt.Println("Got connection, type anything...new line sends and quit quits the session");
wg.Add(1)
go sendRequest(&wg, conn)
wg.Wait()
}
func sendRequest(wg *sync.WaitGroup, conn net.Conn) {
defer wg.Done()
// same code as before
}
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