There is no other way to learn patience, than to be in a situation that requires patience. Taking a cue from the life of our Lord Jesus Christ, Jesus was very patient with his disciples. They were sometimes thickheaded, lazy, selfish, and slow to believe. Even from a merely human standpoint, we can see how frustrating they must have been. How much more irritating it would be for God Incarnate to interact daily with these men. In spite of Jesus' miracles and words of wisdom, they were focused upon themselves and wavered in their belief about who he really was. To say that was uncomfortable for Jesus would be an understatement. Yet do we find him railing at his disciples over their foolishness and stupidity? Or making fun of them when they make mistakes?
Occasionally he does remark that his disciples are slow to believe, or he asks rhetorically how long they will fail to have faith in him, but these are always appropriate reminders about just what was at stake for them. These were fitting and useful rebukes, not petty venting.