Centos – High RAM usage by Apache without any visitors

apache-2.2centoshttpdmemoryMySQL

I have recently bought a VPS server with the below configuration

Centos 6 64bit
20GB SSD
512MB RAM
512 VSwap

I have hosted around 10 websites. In that 4 of them is WordPress. Others are dynamic(PHP) websites. I have a very few visitors. But when I checked the RAM I found that Apache is most of the ram. When apache is running, ram usage is around 97%. While stopping apache, it becomes 30%.

How can I configure apache so that it uses less ram?

I heard that converting InnoDB to MyISAM can solve ram usage. But my MySQL is only using less ram

Best Answer

In my case, I had Apache with mod_php running on a Centos 64bit VM with 2GB RAM. When I initially installed Apache 2.4, everything worked well and the parent Apache process (owned by root) would consume around 10 MB of memory.

Later on, when I checked top, the parent and all child processes were consuming 28% of server memory (around 500 MB each). After fiddling around with many settings and mpm forks and max servers and what not, I finally did yum remove php and restarted Apache. Memory consumption went back to normal 10 MB. This lead me to believe it was a PHP setting causing the problem. So I copied over php.ini from another server and reinstalled PHP (using yum install php) and again everything worked fine. Comparing the two php.ini files, I found that I had earlier linked browscap in php.ini and it was a 60 MB file which would load in memory during startup.

So do check, you may have something similar.

Related Solutions

Mysql – innodb memory usage thesql

You should use 75-80% or RAM as the max buffer pool size if the server is dedicated to doing MySQL

Please place these two lines in /etc/my.cnf (my.ini)

[mysqld]
innodb_buffer_pool_size=200M
innodb_log_file_size=50M

If you want to go with 100MB recommendation for InnoDB then use these instead

[mysqld]
innodb_buffer_pool_size=100M
innodb_log_file_size=25M

Make sure you resize the innodb log files as follows:

service mysql stop
rm -f /var/lib/mysql/ib_logfile*
service mysql start

(Edit: fixed typo in rm command)

Php – Unusually high memory usage on a CentOS VPS with 512 guaranteed RAM

free -m shows that there should be enough free RAM. When a process gets killed because of too few RAM being available, this is called an "oom kill"m where "oom" stands for out of memory.

You can even tell Linux which processes to kill in what order when this situation occurs.

Besides that, MySQL reserves a lot of RAM on our system, which is normal. You can decrease the value by editing the my.cnf file and tuning the various variables of the MySQL config file.

Furthermore you should put some efforts in optimizing Apache in order to keep the RAM consumption low. It heavily depends on your PHP application if Apache and PHP consume much RAM or not.

In addition you should create a SWAP file which helps you in case of your memory running full.

Best Answer

Related Solutions

Mysql – innodb memory usage thesql

Php – Unusually high memory usage on a CentOS VPS with 512 guaranteed RAM

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