Dear Sensei (@Kevin),
At risk of asking a dump question about the Post Request tutorial: What do you mean by threaded replies?
I googled the term, but only got some articles about threading servlets and your very Thread Safety tutorial, which are all neat but don’t really answer my question. Furthermore, it was my understanding that all incoming requests are already threaded by the server - clients do not talk to a Servlet instance, but get their own thread assigned. Or something like that.
If I wanted to stream the chat from your tutorial, I’d personally use a websocket - just for fun, and it seems sensible. Also in that case I’d know how to create a thread for each request on that socket.
Perhaps it is exactly this thought which confuses me about what you mean by threaded replies? 
I did, however, check your Thread Safety tutorial, and will do it in detail soon. But if anything it seems to confirm my suspicion that the requests/replies already run on threads; hence the synchronization of those within that tutorial.
Please help me out on this one!
I confess I don’t always do the homework, but I’d like to at least come up with some concept/ approach in my mind.
