Re: Two questions on httpd tuning (Apache Users)

Hi Martin,

2017-08-17 17:40 GMT+02:00 Martin Knoblauch <knobi@xxxxxxxxxxxx>:

Hi,

this is for httpd-2.4.26 with the mpm_worker_module. I have one practical and one more theoretical question.

First, is there a way to determine the maximum number of concurrent requests that have been processed at any time since the last server (re)start?

I would periodically poll https://httpd.apache.org/docs/2.4/mod/mod_status.html and push metrics to a backend like graphite/prometheus/etc.

Second, if I have the default configuration and I ever want to increase MaxRequestWorkers above 400 my understanding is that I need to either increase ServerLimit or ThreadsPerChild (or adjust both). Which should I touch first (why :-)?

From https://httpd.apache.org/docs/2.4/mod/worker.html:

"ServerLimit is a hard limit on the number of active child processes, and must be greater than or equal to the MaxRequestWorkers directive divided by the ThreadsPerChild directive."

Basically mpm_worker creates some processes (maximum ServerLimit) that in turn spawn ThreadsPerChild threads each, so you need to tune them to reach MaxRequestWorkers.

Hope that helps :)

Luca