[libmicrohttpd] Where are http requests queued?

[Bob Furber]

Would someone be able to tell me if there is a limit to the number of 
connection threads when *http_init*() is initialized with 
/MHD_USE_THREAD_PER_CONNECTION/?

When I torture test my MHD server by bombarding it with xhr requests, I 
can only find evidence of at most 6 simultaneous MHD threads.

The MHD threads transfer their requests to a message queue (for 
processing by main()) and uSnooze-wait for their replies from the main() 
thread before proceeding to post their replies to the client. Normally, 
the main() thread responds as promptly as possible. But, when I put 
main() to sleep for a number of seconds, one would expect the MHD 
threads to back up and the message queue to fill up. But, the message 
queue never gets longer than 6 queue items waiting, whereas many 1000 
requests queue up while main() sleeps and are ALL are eventually 
responded when main() awakes.

What is really interesting in this exercise, is that NO requests are 
lost while main sleeps. They are queued up elsewhere. But, where? In 
MHD? In the processors Ethernet chip/module? And, more importantly, 
where should requests best be queued? Why?

Thanks,

Bob Furber