Can TCP clients receive data after a read timeout? - go

Question

I create a tcp connection pool in golang and set every connection to keep alive, when I get a connection from pool, I will set a 10 seconds timeout by SetDeadline function. Now I want to know, if a timeout error occur after reading from a connection and server send message to me after this point, will the message be put into my connection receive buffer? Will I get the message in next reading? If so, how should I handle the timeout error? Close the connection and create a new one?

Answer 1

If a timeout error occur after reading from a connection and server send message to me after this point, will the message be put into my connection receive buffer?
If you don't close the connection, yes.
Will I get the message in next reading?
Yes, if you reset the deadline. Although this does beg the question why you set a timeout in the first place.
package main
import (
"fmt"
"io"
"log"
"net"
"time"
)
func main() {
l, err := net.Listen("tcp", "127.0.0.1:3001")
check(err)
go slowServer(l)
conn, err := net.Dial("tcp", "127.0.0.1:3001")
check(err)
conn.SetDeadline(time.Now().Add(time.Second))
b := make([]byte, 512)
n, err := conn.Read(b)
fmt.Printf("%q, %v\n", b[:n], err) // "", i/o timeout
// Reset deadline
conn.SetDeadline(time.Now().Add(2 * time.Second))
n, err = conn.Read(b)
fmt.Printf("%q, %v\n", b[:n], err) // "hello world", <nil>
}
func slowServer(l net.Listener) {
conn, err := l.Accept()
check(err)
time.Sleep(2 * time.Second)
io.WriteString(conn, "hello world")
conn.Close()
}
func check(err error) {
if err != nil {
log.Fatal(err)
}
}
// "", read tcp 127.0.0.1:50488->127.0.0.1:3001: i/o timeout
// "hello world", <nil>
Try it on the playground: https://play.golang.org/p/Id60hHK7tKF