Note about limiting concurency in Server

[woytam]

For better understanding of not overwriting LimitConcurency in Server

[WyriHaximus]

Looks like a good start. maybe in a follow up PR review if we still show use Server in the example below

[andyvanee]

I just encountered the same issue, as I was seeing no speedups after 4 concurrent requests. I was using the php docker container which uses the default ini settings of memory_limit = 128M and post_max_size = 8M which results in only 4 concurrent requests.

https://github.com/php/php-src/blob/master/php.ini-development#L401

Since I'm not really handling any uploads, I added the following .ini file, which boosted it to 4096 concurrent requests.

[PHP]

post_max_size = 8K
memory_limit = 256M

The note in the last paragraph of the Server section of the README does cover this already, but I was confused because the automatically added middleware was setting the upper bound.

I am curious about how to calculate a sensible number for concurrent requests and what the failure mode is if I push it too far? I guess I may have to do some more testing 😃

[clue]

@woytam Thank you for filing this PR, I agree that it makes sense to add some documentation for this! 👍

I've just filed #342 to add some additional documentation for the concurrency limit and how to possibly avoid hitting this limit. Let me know what you think about this 👍