gorm 多协程（goroutine）处理数据时报： connect: cannot assign requested address 处理

如下代码：

package main

import (
    "gorm.io/driver/mysql"
    "gorm.io/gorm"
    "gorm.io/gorm/logger"
    "gorm.io/gorm/schema"
    "log"
    "os"
    "sync"
    "time"
)

var db *gorm.DB
var err error

func init() {

    var gormConfig gorm.Config
    gormConfig.NamingStrategy = schema.NamingStrategy{
        SingularTable: true, // use singular table name, table for `User` would be `user` with this option enabled
    }

    sqlLogger := logger.New(
        log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer
        logger.Config{
            SlowThreshold:             time.Second, // Slow SQL threshold
            LogLevel:                  logger.Info, // Log level
            IgnoreRecordNotFoundError: true,        // Ignore ErrRecordNotFound error for logger
            Colorful:                  false,       // Disable color
        },
    )
    gormConfig.Logger = sqlLogger

    //mysql
    var dbDsn = "user:password@tcp(host:3306)/dbname?charset=utf8mb4&parseTime=True&loc=Local"
    // https://gorm.io/docs/gorm_config.html
    db, err = gorm.Open(mysql.Open(dbDsn), &gormConfig)

    if err != nil {
        log.Fatalf("model base init err: %v", err)
    }

    //setConn()
}

func setConn() {
    mysqlDb, err := db.DB()
    if err != nil {
        panic(err)
    }

    mysqlDb.SetMaxIdleConns(20)
    mysqlDb.SetMaxOpenConns(200)
}

func close() {
    mysqlDb, err := db.DB()
    if err != nil {
        panic(err)
    }
    mysqlDb.Close()
}

func modelSelect(wg sync.WaitGroup) {
    defer wg.Done()
    for i := 0; i < 20; i++ {
        var result = make(map[string]interface{}, 0)
        db.Table("test").Where("id=1").Find(&result)
    }
}

func main() {
    var wg sync.WaitGroup
    for i := 0; i < 100; i++ {
        wg.Add(1)
        go modelSelect(wg)
    }
    wg.Wait()
}

当循环此处增加到一定程度的时候，会报 connect: cannot assign requested address 这种错误，可以控制连接池的参数来避免改错误。

如上代码只要打开 setConn的注释即可