insert mysql:1040 too many connections

[zcdj1987]

my test code is this:

package main

import (
"database/sql"
"fmt"
_ "github.com/go-sql-driver/mysql"
"runtime"
"strconv"
"time"
)

var num chan int

var allLogin int

func dbInsert(loginInsert *sql.Stmt, i int) {
_, err := loginInsert.Exec("zc"+strconv.Itoa(i), "123456")
if err != nil {
fmt.Println(strconv.Itoa(i)+"行:", err)
}
num <- 1
}

func main() {
runtime.GOMAXPROCS(runtime.NumCPU())
db, err := sql.Open("mysql", "root:198771zc@tcp(localhost:3306)/mygame?charset=utf8")
if err != nil {
fmt.Println(err)
return
}

num := make(chan int)

//db.SetMaxIdleConns(runtime.NumCPU())

loginInsert, err := db.Prepare("insert into loginer values(null, ?, ?)")

fmt.Println(time.Now())

for i := 0; i < 1000; i++ {
    go dbInsert(loginInsert, i)
}
for {
    select {
    case <-num:
        allLogin++
    }
    if allLogin == 1000 {
        fmt.Println(time.Now())
        break
    }
}
time.Sleep(time.Minute)

}

I used dbPrepare and .Exec
I read the guide it says the *Stmt is thread-safe
So can you help me to solve the problem,how can I safe use the db int goruntine?

[julienschmidt]

You have more concurrent connections / queries than your server allows. See https://code.google.com/p/go/issues/detail?id=4805

For now, you have to limit the concurrency manually somehow, e.g. via a Channel "semaphore": http://golang.org/doc/effective_go.html#channels

[julienschmidt]

Duplicate of #111