I don’t think it’s println’s nested locks causing “aa” not to be printed at all; locking would affect task printing order. It’s just your script’s primary task ending and closing the process when your @async task yielded control midway. That’s just something you always need to account for when you run a script from the command line. I think enclosing the tasks in @sync begin ... end would work as well as wait, and it’s more convenient to do once over multiple tasks.
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