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
<IfModule prefork.c>
StartServers      8
MinSpareServers   5
MaxSpareServers   20
ServerLimit      2000
MaxClients       5000
MaxRequestsPerChild  4000
</IfModule>

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:

<IfModule prefork.c>
StartServers      200
MinSpareServers   50
MaxSpareServers   200
ServerLimit      400
MaxClients       1000
MaxRequestsPerChild  0
</IfModule>


 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

  • qemu: could not load PC BIOS 'bios-256k.bin' solution
  • Proxmox How To Custom Partition During Install
  • Hyper-V Linux VM Boots to Black Screen, Storage, NIC Not Found Issues
  • Ubuntu Mint How to Fix Missing/Broken /dev and /dev/pts which causes terminal to immediately close exit and not work
  • How high can a Xeon CPU get?
  • bash fix PATH environment variable "command not found" solution
  • Ubuntu Linux Mint Debian Redhat Youtube Cannot Play HD or 4K videos, dropped frames or high CPU usage with Nvidia or AMD Driver
  • hostapd example configuration for high speed AC on 5GHz using WPA2
  • hostapd how to enable and use WPS to connect wireless devices like printers
  • Dell Server Workstation iDRAC Dead after Firmware Update Solution R720, R320, R730
  • Cloned VM/Server/Computer in Linux won't boot and goes to initramfs busybox Solution
  • How To Add Windows 7 8 10 11 to GRUB Boot List Dual Booting
  • How to configure OpenDKIM on Linux with Postfix and setup bind zonefile
  • Debian Ubuntu 10/11/12 Linux how to get tftpd-hpa server setup tutorial
  • efibootmgr: option requires an argument -- 'd' efibootmgr version 15 grub-install.real: error: efibootmgr failed to register the boot entry: Operation not permitted.
  • Apache Error Won't start SSL Cert Issue Solution Unable to configure verify locations for client authentication SSL Library Error: 151441510 error:0906D066:PEM routines:PEM_read_bio:bad end line SSL Library Error: 185090057 error:0B084009:x509 certif
  • Linux Debian Mint Ubuntu Bridge br0 gets random IP
  • redis requirements
  • How to kill a docker swarm
  • docker swarm silly issues