You're not alone. My daughter is only 5 but she is super eager to learn everything! She's very bright but she is definitely a perfectionist. I can sometimes see frustration mounting in her body language (the look on her face, fidgeting, etc) and sometimes I just can feel it which is hard to explain. But most of the time it's tears. I have also tried helping her notice before she gets to that point but I think it's a far shot at this age.
I mean realistically, I don't even realize I'm frustrated until I'm acting like a 5 year old. :)
What has helped is validating her frustration. I make a point to express that learning new things can be frustrating, that I often experience frustration and that it is okay and acceptable to be frustrated. Sometimes I tell a funny story of how I acted when I was frustrated over something and it helps her feel better that even I, as her mom, lose my ability to control my emotions. I try never to tell her it isn't a big deal or try to manipulate her out of her frustration because I know that when I'm frustrated I don't appreciate someone telling me to "get over it" or "it's not that big of a deal", etc. Obviously, when we're calm, it is easier to look back and realize those things for ourselves but when in the midst of frustration it tends to only aggravate the situation.