Quoting Carter Kozak <c4kofony(a)gmail.com>:
When I run the test case locally I immediately see 1-8 printed.
Perhaps there aren't many cores available on your test machine?
The test machine is an 8 core machine.
Also note that writing the response is handled asynchronously, so it's
likely not a very large percentage of the total request handling time
spent inside your HttpHandler implementation.
Do you think the 1 second sleep in the body is not sufficient?
-- Matt