[GauntletWizard]

Your use of the waitgroup is off; Because the Add instruction is inside the goroutine, it may not run until after wg.Done is called, which will return immediately.

Still, that made it less flaky for a bit, but the it printed again! And I realized what else is going on: There's actually time between when the deferred functions are executed and the program exits! Which is fascinating, but unlikely to matter in practice. It brings me to another question: do deferred statements still get called when there's a panic on a different goroutine? And the answer seems to be no; adding a deferred print to the main function does not print.

[kodah]

You're right about the Add(1) and defer. defer in itself is pretty interesting in how it's called. Basically there's the main body of your function and then a list of things to do before return, of which defers get added to. So, your theory is correct.

I think intuitively I probably knew that a panic in a goroutine will shut down the main thread, it just didn't occur logically to me when I read it; which is an interesting paradox. Maybe that's a me-thing though.