Apache MPM worker vs prefork

find what MPM Apache is using, it will either be using "worker" or "prefork"

apachectl -l
Compiled in modules:
core.c
prefork.c
http_core.c
mod_so.c


In my case it is "prefork"

vi /etc/httpd/conf/httpd.conf

Find the section that looks like this (by default one will normally exist for prefork and for worker, but in my case I only care about prefork since prefork is what is compiled in):

# prefork MPM
# StartServers: number of server processes to start
# MinSpareServers: minimum number of server processes which are kept spare
# MaxSpareServers: maximum number of server processes which are kept spare
# ServerLimit: maximum value for MaxClients for the lifetime of the server
# MaxClients: maximum number of server processes allowed to start
# MaxRequestsPerChild: maximum number of requests a server process serves

StartServers 8
MinSpareServers 5
MaxSpareServers 20
ServerLimit 2000
MaxClients 5000
MaxRequestsPerChild 4000


As some have mentioned the MPM prefork/worker sections are VERY important they affect both stability and performance.
In my case I'm the most concerned because I keep getting the MaxClients error message/hung Apache process without error (where Apache thinks it's running but can't connect and yet most of the time nothing in the debug log shows a problem).

Enable Debug:

Speaking of that you might want to enable this for debugging if you're having the issues I've seen (the crash but even with debug it often won't show the true error)

Add this to your config file: Loglevel debug

Back to the issue, prefork means a new process/server is started for each new connection to the web server.

My new settings:


StartServers 200
MinSpareServers 50
MaxSpareServers 200
ServerLimit 400
MaxClients 1000
MaxRequestsPerChild 0



WARNING: MaxClients of 1000 exceeds ServerLimit value of 400 servers,
lowering MaxClients to 400. To increase, please see the ServerLimit
directive.

Change ServerLimit to "4000" and restart


Tags:

apache, mpm, vs, preforkfind, quot, prefork, apachectl, compiled, modules, http_core, mod_so, vi, etc, httpd, conf, default, startservers, server, processes, minspareservers, maxspareservers, maximum, serverlimit, maxclients, maxrequestsperchild, requests, serves, ifmodule, sections, stability, debug, enable, debugging, ve, config, loglevel, settings, exceeds, servers, lowering, directive, restart,

Latest Articles

  • CentOS 8 how to restart the network!
  • CentOS 8 how to convert to a bootable mdadm RAID software array
  • ADATA USB Thumb Drive Issues
  • KMODE EXCEPTION NOT HANDLED - QEMU/KVM Won't Boot Windows 2016 or 10 Image or Physical Machine
  • Linux Mint / Ubuntu / Debian Mate Disable Guest Session and Hide Usernames on Lightdm Login screen GUI
  • SSH How To Create Public/Private Key Pair and with a Larger Keysize than 2048 bits
  • selenium.common.exceptions.WebDriverException: Message: Can not connect to the Service geckodriver
  • python ModuleNotFoundError: No module named 'bs4' even though you have the module
  • ssh how to connect using a SOCKS 5 proxy with nc and proxycommand
  • Enable AMDGPU Linux Driver
  • apache symlinks denied even with followsymlinks
  • chown how to change ownership on a symlink
  • how to use ifplugd in Linux to execute a command or script when a NIC cable is unplugged or plugged in
  • dd how to backup and restore disk images including compression with gzip
  • mpv / mplayer with Radeon / AMD GPU Video Card Driver enable VDPAU GPU Accelerated Video Decoding
  • Wordpress Reset Blog User Password from MySQL Using Linux Bash and not PHPMyadmin
  • Ubuntu Linux Mint Debian xorg performance and tear-free tuning for AMD Radeon Based Cards
  • Centos 7 Stopped and Disabled Firewalld and ports still blocked
  • MariaDB / MySQL Reset Root Forgotten Password on Centos 7
  • Centos 7 How to install Mysql/Mariadb