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