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net: mass tcp dial timeout with the concurrency more than 10000 #32761

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Anteoy opened this issue Jun 25, 2019 · 9 comments

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@Anteoy
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@Anteoy Anteoy commented Jun 25, 2019

What version of Go are you using (go version)?

$ go version
go version go1.12.1 linux/amd64

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GOARCH="amd64"
GOBIN="/home/zhoudazhuang/gobin/"
GOCACHE="/home/zhoudazhuang/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/zhoudazhuang/db11/jm/pro"
GOPROXY=""
GORACE=""
GOROOT="/home/zhoudazhuang/usr/local/go1.12.1/go"
GOTMPDIR=""
GOTOOLDIR="/home/zhoudazhuang/usr/local/go1.12.1/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build631445118=/tmp/go-build -gno-record-gcc-switches"

What did you do?

My tested code:
Server:

func main() {
	l, err := net.Listen("tcp", ":8888")
	if err != nil {
		log.Println("listen error:", err)
		return
	}

	for {
		c, err := l.Accept()
		if err != nil {
			log.Println("accept error:", err)
			break
		}
		go c.Close()
		// start a new goroutine to handle
		// the new connection.
		//log.Println("accept a new connection")
		//go handleConn(c)
	}
}

Client:

package main

import (
	"fmt"
	"github.com/jessevdk/go-flags"
	"net"
	"os"
	"sync"
	"time"
)

var args struct {
	Addr string `short:"a"  required:"yes" description:"服务端地址"`
	Concurrence int `short:"c"  required:"yes" description:"并发请求数"`
	Count int `short:"t" required:"yes" description:"测试次数"`
}

func main() {
	argParser := flags.NewNamedParser("tcp_test", flags.PassDoubleDash)
	argParser.AddGroup("Mock parameters", "", &args)
	_, err := argParser.Parse()
	if err != nil {
		fmt.Println(err)
		argParser.WriteHelp(os.Stdout)
		os.Exit(1)
	}
	fmt.Printf("测试参数: %+v\n",args)
	wg := sync.WaitGroup{}
	for j:=0; j<args.Count;j++ {
		for i:=0; i<args.Concurrence;i++{
			wg.Add(1)
			go func() {
				defer wg.Done()
				time.Sleep(time.Second*5)
				conn, err := net.DialTimeout("tcp", args.Addr, time.Second*3)
				if err != nil {
					fmt.Printf("dialog err: %+v i为%d:\n",err,j)
					return
				}
				time.Sleep(time.Millisecond*10)
				conn.Close()
			}()
		}
	}
	fmt.Println("start wait")
	wg.Wait()
	fmt.Println("ok")
}

The cmd: ./Test -a 127.0.0.1:8888 -c 10000 -t 3
╰─># cat /proc/sys/net/ipv4/ip_local_port_range
4096 65535
╰─># ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 386849
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 10000000
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 1000000
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited

╰─># free -h
total used free shared buffers cached
Mem: 94G 85G 9.3G 2.0M 54M 42G
-/+ buffers/cache: 42G 51G
Swap: 0B 0B 0B

╰─># lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 32
On-line CPU(s) list: 0-31
Thread(s) per core: 2
Core(s) per socket: 8
Socket(s): 2
NUMA node(s): 2
Vendor ID: GenuineIntel
CPU family: 6
Model: 79
Model name: Intel(R) Xeon(R) CPU E5-26xx v4
Stepping: 1
CPU MHz: 3192.606
BogoMIPS: 6385.21
Hypervisor vendor: KVM
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 4096K
NUMA node0 CPU(s): 0-15
NUMA node1 CPU(s): 16-31

What did you expect to see?

no tcp dial timeout.

What did you see instead?

dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:
dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:
dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:
dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:

@Anteoy

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@Anteoy Anteoy commented Jun 25, 2019

|># cat /proc/sys/net/ipv4/tcp_max_syn_backlog
65536
|># cat /proc/sys/net/core/somaxconn
16384

@av86743

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@av86743 av86743 commented Jun 25, 2019

Does this also happen with go 1.11? For server part, presumably.

@Anteoy

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@Anteoy Anteoy commented Jun 25, 2019

@av86743 I don't have go 1.11, You can try it.
I am suspicious of the performance bottleneck.

@av86743

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@av86743 av86743 commented Jun 25, 2019

You must test your code with latest version of go 1.11 and provide results, in order to to make your request meaningful and yourself helpful to Go community.

@Anteoy

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@Anteoy Anteoy commented Jun 25, 2019

@av86743 The lastest version is 1.12.6, not 1.11.

@Anteoy

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@Anteoy Anteoy commented Jun 25, 2019

I also tested it at go 1.10.8. It got the same result. I don't think it's related to the version, It seems to be related to performance bottlenecks.

@av86743

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@av86743 av86743 commented Jun 25, 2019

Provided server source won't even compile.
Server output is not provided.

@Anteoy

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@Anteoy Anteoy commented Jun 25, 2019

I put the Server output at "What did you see instead?"

dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:
dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:
dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:
dialog err: dial tcp 127.0.0.1:8888: i/o timeout i为3:

"Provided server source won't even compile."
You mean my server code can not compile correctly?

func main() {
	l, err := net.Listen("tcp", ":8888")
	if err != nil {
		log.Println("listen error:", err)
		return
	}

	for {
		c, err := l.Accept()
		if err != nil {
			log.Println("accept error:", err)
			break
		}
		go c.Close()
		// start a new goroutine to handle
		// the new connection.
		//log.Println("accept a new connection")
		//go handleConn(c)
	}
}
@andybons andybons added this to the Unplanned milestone Jun 25, 2019
@andybons andybons changed the title mass tcp dial timeout with the concurrency more than 10000 net: mass tcp dial timeout with the concurrency more than 10000 Jun 25, 2019
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@andybons andybons commented Jun 25, 2019

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