Nginx + php-fpm: where does the queue for processes accumulate and can this queue be monitored?

Question

PHP

I'm doing load testing of nginx + php-fpm configuration.
The question arose:

For example, 1,000 requests arrive in nginx at the same time.
Let php-fpm be able to process 100 requests at the same time.

What happens to the other 900 requests while php-fpm processes the first batch?
That is, where exactly is the queue accumulating? Does Nginx proxy the entire incoming batch of requests to php-fpm at once? Or it keeps a queue and waits for managers to be released to process requests from the queue.

And the second question: where and how can you observe this queue? Through htop is not visible for obvious reasons))

Answer 1

Nginx has native monitoring NGINX Monitoring , in particular, you can see the number of active and pending connections.

Answer 2

With the remaining 900 requests, most likely, a 504 will occur. To spread the load, you can use the limit_req nginx module .

Answer 3

Connect some kind of queue server, similar to the same beansolk and shove it with a worker and monitor the work process