[tdg]

Goroutines are extremely lightweight. It is common to run hundreds of thousands of them on one machine. (The main reason for that is goroutines start off with a very small stack and extend it as necessary)

It is up to executorService to decide how many threads to use to execute those tasks. But they will be executed in threads. So you are unlikely to have more than a few hundred(maybe a few thousand?) of them around at any time.