package main

import (
    "time"

    "fmt"

    "gopkg.in/mgo.v2"
)

func main() {
    // No connections
    // db.serverStatus().connections.current = 6

    mongoSession := connectMGO("localhost", "27017", "admin")
    // 1 new connection created
    //db.serverStatus().connections.current = 7

    produceDataMGO(mongoSession)
    produceDataMGO(mongoSession)
    produceDataMGO(mongoSession)
    produceDataMGO(mongoSession)
    // 4 new connections created and closed
    // db.serverStatus().connections.current = 7

    go produceDataMGO(mongoSession)
    go produceDataMGO(mongoSession)
    go produceDataMGO(mongoSession)
    go produceDataMGO(mongoSession)
    // 4 new connections created and closed concurrently
    // db.serverStatus().connections.current = 10

    time.Sleep(time.Hour * 24) // wait any amount of time
    // db.serverStatus().connections.current = 10
}

func connectMGO(host, port, dbName string) *mgo.Session {
    session, _ := mgo.DialWithInfo(&mgo.DialInfo{
        Addrs:    []string{fmt.Sprintf("%s:%s", host, port)},
        Timeout:  10 * time.Second,
        Database: dbName,
        Username: "",
        Password: "",
    })
    return session
}

func produceDataMGO(conn *mgo.Session) {
    dbConn := conn.Copy()
    dbConn.DB("").C("test").Insert("")
    dbConn.Close()
}