net: problem with Close and final packet delivery #3746
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Here is even simpler program to demonstrate your issue:
package rpc
import (
"net/http"
"net"
"testing"
)
func TestALEX(t *testing.T) {
arith := new(Arith)
Register(arith)
HandleHTTP()
l, e := net.Listen("tcp", "127.0.0.1:0")
if e != nil {
t.Fatalf("listen error: %v", e)
}
defer l.Close()
go http.Serve(l, nil)
client, err := DialHTTP("tcp", l.Addr().String())
if err != nil {
t.Fatalf("dialing: %v", err)
}
defer client.Close()
args := Args{17, 8}
var reply Reply
err = client.Call("Arith.Mul", args, &reply)
if err != nil {
t.Fatal("arith error:", err)
}
t.Logf("Arith: %d*%d=%d\n", args.A, args.B, reply)
}
I think the problem here is, we do not use tcp as intended. Here is pure net test to
demonstrate what is happening:
package net
import (
"io"
"testing"
"time"
)
func TestALEX(t *testing.T) {
l, e := Listen("tcp", "127.0.0.1:0")
if e != nil {
t.Fatal(e)
}
defer l.Close()
read := func(r io.Reader) (byte, error) {
var m [1]byte
_, e = io.ReadFull(r, m[:])
return m[0], e
}
write := func(w io.Writer, m byte) {
_, e = w.Write([]byte{m})
if e != nil {
t.Fatal(e)
}
}
ch := make(chan error)
go func() {
c, e := l.Accept()
if e != nil {
t.Fatal(e)
}
defer c.Close()
for e == nil {
_, e = read(c)
}
ch <- e
}()
c, err := Dial("tcp", l.Addr().String())
if err != nil {
t.Fatal(e)
}
write(c, 'A')
go read(c)
time.Sleep(10 * time.Millisecond)
c.Close()
e = <-ch
if e != nil && e != io.EOF {
t.Fatal(e)
}
}
This test fails because tcp connection is reset by c.Close. We should really use
c.(*TCPConn).CloseWrite() instead. But we do not. In net/rpc and in net/http/fcgi
(https://golang.org/issue/3710) we assume that tcp connection can
just be closed and final bits of conversation will reach their destination reliably. But
here we see connection is reset, so tcp peers are out of sync and confused.
We could change our windows network code to ignore these read errors - rewrite this
error code into io.EOF, but I am not sure if this is always appropriate. This suggestion
will not help when we hurt other programs, like in
https://golang.org/issue/3710.
I am not sure what to do.
Alex
Status changed to Accepted. |
|
Comment 3 by support@ryron.org: and can not connect to other device. both writing by golang |
http://golang.org/cl/6604072 Owner changed to @alexbrainman. Status changed to Started. |
|
This issue was closed by revision fa3e4fc. Status changed to Fixed. |
I've done a same tutorial he did. but the problem is not fixed, yet. You can see the RPC tutorial here. http://jan.newmarch.name/go/rpc/chapter-rpc.html I had exactly a same error as he'd written before. rpc: rpc: server cannot decode request: WSARecv tcp 127.0.0.1:1234: The specified network name is no longer available. Attachments:
|
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by feixings:
latest version of Go:1.0.1 、1.0.2 What steps will reproduce the problem? 1.cd C:\Go\src\pkg\net\rpc\jsonrpc 2.go test What is the expected output? test no pass What do you see instead? rpc:server cannot decode request Which compiler are you using (5g, 6g, 8g, gccgo)? 8g Which operating system are you using? windows 7 Which version are you using? (run 'go version') 1.0.2 Please provide any additional information below. /** * ArithClient */ package main import ( "net/rpc" "fmt" "log" ) type Args struct { A, B int } type Quotient struct { Quo, Rem int } func main() { client, err := rpc.DialHTTP("tcp", "127.0.0.1:1234") if err != nil { log.Fatal("dialing:", err) } // Synchronous call args := Args{17, 8} var reply int err = client.Call("Arith.Multiply", args, &reply) if err != nil { log.Fatal("arith error:", err) } fmt.Printf("Arith: %d*%d=%d\n", args.A, args.B, reply) var quot Quotient err = client.Call("Arith.Divide", args, ") if err != nil { log.Fatal("arith error:", err) } fmt.Printf("Arith: %d/%d=%d remainder %d\n", args.A, args.B, quot.Quo, quot.Rem) } /** * ArithServer */ package main import ( "fmt" "net/rpc" "errors" "net/http" ) type Args struct { A, B int } type Quotient struct { Quo, Rem int } type Arith int func (t *Arith) Multiply(args *Args, reply *int) error { *reply = args.A * args.B return nil } func (t *Arith) Divide(args *Args, quo *Quotient) error { if args.B == 0 { return errors.New("divide by zero") } quo.Quo = args.A / args.B quo.Rem = args.A % args.B return nil } func main() { arith := new(Arith) rpc.Register(arith) rpc.HandleHTTP() err := http.ListenAndServe(":1234", nil) if err != nil { fmt.Println(err.Error()) } } run result: rpc:server cannot decode request:WSARecv tcp 127.0.0.1:1234:The specified network name is no langer available.Attachments:
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