达到最大连接数后不插入数据

I have created a mysql connection in Go, where I set:

SetMaxIdleConns to 10
SetMaxOpenConns to 200
SetConnMaxLifetime to 15 * time.Second

After running script, I observed that no insert query is running after 200 connections.

func GetDbh(conf goini.SectionMap) (db *sql.DB) {
    db, err := sql.Open("mysql", dbUser+":"+dbPass+"@tcp("+dbServer+":3306)/"+dbName)
    if err != nil {
        fmt.Println("Exit. Cannot make connection with host: '" + dbServer + "' user: '" + dbUser + "' pass: '" + dbPass + "' database '" + dbName + "'")
        return nil
    }
    db.SetMaxIdleConns(10)
    db.SetMaxOpenConns(200)
    db.SetConnMaxLifetime(15 * time.Second)
    return db
}

MariaDB [test]> show status where `variable_name` = 'Threads_connected';
+-------------------+-------+
| Variable_name     | Value |
+-------------------+-------+
| Threads_connected | 201   |
+-------------------+-------+

Below code insert data into mysql

package main
import (
    dbh "../lib/dbutils"
)

func main() {
dbm := dbh.GetDbh(conf)

.
.
for loop <which runs more than 500 times> {
.
. <here is some code which calculate date, id, email and salary>
.
query_update_insert := "INSERT INTO employee(id,date,email,salary) values("+strconv.FormatInt(id,10)+",'"+mdate+"','"+email+"',"+strconv.FormatInt(salary,10)+") ON DUPLICATE KEY UPDATE salary=VALUES(salary);"
                                fmt.Println("Insert(employee) Query:"+query_update_insert)
                                _, err := dbm.Query(query_update_insert)
                                if err != nil {
                                        fmt.Println("Insert Error: "+err.Error())
            }
   }
dbm.Close()
}

If I reduce SetConnMaxLifetime to Nanosecond or less than 5 seconds it gives following error:

Insert Error: Error 1040: Too many connections
Insert(employee) Query:INSERT INTO employee(id,date,email,salary) values(416,'2019-09-24','naresh_t@sharekhan.com',60000) ON DUPLICATE KEY UPDATE salary=VALUES(salary);
Insert Error: Error 1040: Too many connections
Insert(employee) Query:INSERT INTO employee(id,date,email,salary) values(416,'2019-09-24','madanlal@sharekhan.com',40000) ON DUPLICATE KEY UPDATE salary=VALUES(salary);

All insert queries should run properly.