fl2.go

package main

import (
    "database/sql"
    "sync"
)

var connectionPool = sync.Pool{
    New: func() interface{} {
        db, _ := sql.Open("postgres", "user=postgres dbname=mydb sslmode=disable")
        return db
    },
}

func main() {
    // Get a connection from the pool
    db := connectionPool.Get().(*sql.DB)
    defer connectionPool.Put(db)
    // Use the connection
    _, _ = db.Exec("SELECT 1")
}