Apache processes

Sources

http://forums.debian.net/viewtopic.php?f=16&t=54688

https://fuscata.com/kb/set-maxclients-apache-prefork

Recognize that Ubuntu 14.04 uses Apache 2 with PHP running through an mpm_prefork module, of which an editable file is in /etc/apache2/mods-enabled/mpm_prefork.conf. Also, recognize that starting in Apache 2.4, MaxClients is now renamed as MaxRequestWorkers, and so any documentation regarding MaxClients needs to be switched to MaxRequestWorkers.

It looks like 14.04 already sets this to 150 so issue evaporated.

1) install ps_mem.py to check memory usage

open a terminal and use the following commands

CODE: SELECT ALL: wget http://www.pixelbeat.org/scripts/ps_mem.py su mv ps_mem.py /usr/local/sbin/ chmod 755 /usr/local/sbin/ps_mem.py

after you do that... as a user you can use the command ps_mem.py to check memory usage

result :

root@mut7:/etc/apache2# su -c ps_mem.py
Private + Shared = RAM used Program4.0 KiB + 25.0 KiB = 29.0 KiB xinetd
4.0 KiB + 38.5 KiB = 42.5 KiB upstart-socket-bridge
..
88.0 KiB + 813.0 KiB = 901.0 KiB php5-fpm (5)
..
12.9 MiB + 13.5 MiB = 26.5 MiB /usr/sbin/apach (8)
..
160.1 MiB + 155.0 KiB = 160.3 MiB mysqld
248.8 MiB + 9.7 MiB = 258.5 MiB php-cgi (10)
347.1 MiB + 232.0 KiB = 347.3 MiB clamd
---------------------------------
893.6 MiB

Here we see apache2 is actually " php-cgi" with 10 processes running taking 258MiB so 25MB/process

Machien has 4GB, leave 1,5 GB for Mysql and rest : so 2,5GB/25MB = 100. We could set MaxClients to 100. Setting it to 50

To watch this dynamically we can do :

watch -n 1 "echo -n 'Apache Processes: ' && ps -C php-cgi --no-headers | wc -l && free -m"

Result :

Every 1.0s: echo -n 'Apache Processes: ' && ps -C php-cgi --no-headers | wc -l && free -m Sat Oct 22 11:18:27 2016

Apache Processes: 10
total used free shared buffers cached
Mem: 4096 3166 929 0 0 2113
-/+ buffers/cache: 1053 3042
Swap: 2048 155 1892

2) How To Change the Value MaxClients

The MaxClients value is located in the main Apache configuration file, typically /etc/apache2/apache2.conf (or /etc/httpd/httpd.conf.)

The relevant section looks like this:

# 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
# MaxClients: maximum number of server processes allowed to start
# MaxRequestsPerChild: maximum number of requests a server process serves
<IfModule mpm_prefork_module>
    StartServers        5
    MinSpareServers     5
    MaxSpareServers     10
    MaxClients          150
    MaxRequestsPerChild 0
</IfModule>

After changing the value, save the file and restart Apache with apache2ctl graceful-stop && apache2ctl start

mut7 : /etc/apache2/apache2.conf

Calcul above. Setting to 50 in 3 places :

<IfModule mpm_prefork_module>
StartServers 1
MinSpareServers 1
MaxSpareServers 5
MaxClients 50
MaxRequestsPerChild 0
</IfModule>

<IfModule mpm_worker_module>
StartServers 1
MinSpareThreads 1
MaxSpareThreads 4
ThreadLimit 64
ThreadsPerChild 25
MaxClients 50
MaxRequestsPerChild 0
</IfModule>
<IfModule mpm_event_module>
StartServers 1
MinSpareThreads 1
MaxSpareThreads 4
ThreadLimit 64
ThreadsPerChild 25
MaxClients 50
MaxRequestsPerChild 0
</IfModule>

service apache2 restart