t.Errorf("closes = %d; want 0", closes)
	}
	if g, w := db.numFreeConns(), 2; g != w {
		t.Errorf("free conns = %d; want %d", g, w)
	}

	// Expire first conn
	offset = 11 * time.Second
	db.SetConnMaxLifetime(10 * time.Second)

	tx, err = db.Begin()
	if err != nil {
		t.Fatal(err)
	}
	tx2, err = db.Begin()
	if err != nil {
		t.Fatal(err)
	}
	tx.Commit()
	tx2.Commit()

	db.mu.Unlock()
	if syncMaxIdle {
		db.SetMaxIdleConns(n)
	}
}

// SetConnMaxLifetime sets the maximum amount of time a connection may be reused.
//
// Expired connections may be closed lazily before reuse.
//
// If d <= 0, connections are not closed due to a connection's age.
func (db *DB) SetConnMaxLifetime(d time.Duration) {
	if d < 0 {
		d = 0
	}
	db.mu.Lock()