2017. december 18., hétfő 13:51:26 UTC+1 időpontban eric.sh...@gmail.com a
következőt írta:
>
> I try to implement a golang tcp server, and I found the concurrency is
> satisfied for me, but the CPU usage is too high(concurrency is 15W+/s, but
> the CPU usage is about 800% in a 24 cores linux machine). At the same time,
> a C++ tcp server is only about 200% usage with a similar concurrency(with
> libevent).
>
> The following code is the demo of golang:
>
> func main() {
> listen, err := net.Listen("tcp", "0.0.0.0:17379")
> if err != nil {
> fmt.Errorf(err.Error())
> }
> go acceptClient(listen)
> var channel2 = make(chan bool)
> <-channel2}
>
> func acceptClient(listen net.Listener) {
> for {
> sock, err := listen.Accept()
> if err != nil {
> fmt.Errorf(err.Error())
> }
> tcp := sock.(*net.TCPConn)
> tcp.SetNoDelay(true)
> var channel = make(chan bool, 10)
>
>
why buffered? Who will close it?
> go read(channel, sock.(*net.TCPConn))
> go write(channel, sock.(*net.TCPConn))
> }}
>
> func read(channel chan bool, sock *net.TCPConn) {
> count := 0
> for {
> var buf = make([]byte, 1024)
>
>
Why allocate a new slice on every iteration?
> n, err := sock.Read(buf)
>
>
This will be slow: TCP is a streaming protocol, so this Read can read any
length between 0 (! yes !) and 1024 bytes.
Use buffering (bytes.NewReader) and some kind of message separation (e.g.
bufio.Scanner for a line-oriented protocol).
>
> if err != nil {
> close(channel)
> sock.CloseRead()
> return
> }
> count += n
> x := count / 58
> count = count % 58
> for i := 0; i < x; i++ {
> channel <- true
> }
> }}
>
> func write(channel chan bool, sock *net.TCPConn) {
> buf := []byte("+OK\r\n")
> defer func() {
> sock.CloseWrite()
> recover()
> }()
> for {
> _, ok := <-channel
> if !ok {
> return
> }
> _, writeError := sock.Write(buf)
> if writeError != nil {
> return
> }
> }}
>
> And I test this tcp server by the redis-benchmark with multi-clients:
>
> redis-benchmark -h 10.100.45.2 -p 17379 -n 1000 -q script load
> "redis.call('set','aaa','aaa')"
>
> I also analyzed my golang code by the pprof, it is said CPU cost a lot of
> time on syscall:
>
>
> <https://lh3.googleusercontent.com/-Xe7U4uSDwK8/Wjc25XRiF5I/AAAAAAAAAAc/ImuGGSAShmkVHEt2f-eTr2KO_OjunZuCQCLcBGAs/s1600/%25E6%2580%25A7%25E8%2583%25BD%25E5%25AE%259E%25E4%25BE%258B.png>
>
>
>
Next time please include the FULL svg, not only the node you think
important!
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