Is there a way to write down the algorithm of multi-threaded programs in a compact and visual way?

Question

Documentation

First of all, we are interested in options with a textual representation.

Answer 1

www.codeuml.com

Answer 2

And what is wrong?

Поток 1
пока x < 10
  x = x + 10
вернуть x * x

Поток 2
пока x > 10
  x = x - 10
вернуть sqrt(x)

Ждать(x = поток1, y = поток2)
вывод x + y

A complete flight of fancy, the recording of the algorithm is just a formal system, you are free to invent anything.