performance - Apache consuming too much CPU and memory

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I am having some troubles with CPU
loading an memory with Apache Web Server.

We are
running a Ubuntu Server 12.04 LTS on a Virtual Machine. Our
server have the following
specs:

• 8GB
  RAM;


• 4 vCPUs
  (12ghz);

We
configured the server to run a Drupal (7.23) based website.
So, we installed Apache, PHP, MySQL... The versions are
below:

• Apache
  2.2.22;


• PHP 5.3.10 (The PHP are running as
  Apache Module.);


• APC
  3.1.7;


• MySQL 5.5.31 (all innodb
  tables);

I am
running some apache modules too. Take a look
(apachectl
-M):

• core_module
  (static)


• log_config_module
  (static)


• logio_module
  (static)


• mpm_prefork_module
  (static)


• http_module
  (static)


• so_module
  (static)



• actions_module
  (shared)


• alias_module
  (shared)


• authz_host_module
  (shared)


• deflate_module
  (shared)


• dir_module
  (shared)


• env_module
  (shared)


• include_module
  (shared)


• mime_module
  (shared)


• php5_module
  (shared)


• proxy_module
  (shared)



• proxy_http_module
  (shared)


• reqtimeout_module
  (shared)


• rewrite_module
  (shared)


• setenvif_module
  (shared)


• ssl_module
  (shared)


• status_module
  (shared)

On
apache2.conf, we have this
config:

 Timeout
            90
 KeepAlive On
 MaxKeepAliveRequests 80

            KeepAliveTimeout 5
 HostnameLookups Off
 LogLevel
            warn

 
 StartServers
            10
 MinSpareServers 10

 MaxSpareServers 30

            MaxClients 120
 MaxRequestsPerChild 1000

            

The
Virtual Host of my
site:

             *:80>
 ServerName blabla.bla.bla

 ServerAdmin
            bla@bla.com
 DocumentRoot /l/disk0/site/public_html


            
 AllowOverride None

            

             /l/disk0/site/public_html>
 Options MultiViews Indexes Includes
            FollowSymLinks ExecCGI
 AllowOverride All

 Order
            allow,deny
 allow from all
 


            LogLevel warn
 ErrorLog "/l/disk0/site/logs/apache/site/error.log"

            CustomLog "/l/disk0/site/logs/apache/sit/access.log" combined
 SSLProxyEngine
            on
 RewriteEngine on
 RewriteLog
            logs/rewrite_www_log

 RewriteLogLevel 0


            Include
            rewrites-www.conf

Drupal
Modules:

• ACL
  7.x-1.0



• APC - Alternative PHP Cache
  7.x-1.0-beta4


• Boost
  7.x-1.0-beta2


• Cache Expiration
  7.x-2.0-beta2


• CAPTCHA
  7.x-1.0


• Chaos tool suite (ctools)
  7.x-1.3


• Date
  7.x-2.6


• Domain Access
  7.x-3.10


• Domain Blocks
  7.x-2.0


• Domain CTools
  7.x-1.3


• Domain Locale
  7.x-1.0-beta3



• Domain Taxonomy 7.x-3.x-dev
  (2012-abr-29)


• Domain Views
  7.x-1.5


• Embed Views Display
  7.x-1.2


• Entity API
  7.x-1.2


• Entity reference
  7.x-1.0


• IMCE 7.x-1.7


• IMCE
  Mkdir 7.x-1.0


• Internationalization
  7.x-1.10


• Link
  7.x-1.1


• Localization update
  7.x-1.0-beta3



• Media
  7.x-1.3


• Meta tags quick
  7.x-2.7


• Newsletter
  7.x-1.0-beta9


• Options Element
  7.x-1.9


• Page Style
  7.x-1.0


• Panels
  7.x-3.3


• Pathauto
  7.x-1.2


• pathologic
  7.x-2.11


• profile2 7.x-1.3+0-dev
  (2013-mai-24)


• select_or_other
  7.x-2.19



• sheetnode 7.x-1.0-beta4+3-dev
  (2013-mai-25)


• SMTP Authentication Support
  7.x-1.0


• Token
  7.x-1.5


• Transliteration
  7.x-3.1


• Variable
  7.x-2.3


• Views
  7.x-3.7


• Vocabulary Permissions Per Role
  7.x-1.0


• Webform
  7.x-3.19


• Webform Validation
  7.x-1.2


• workbench
  7.x-1.2



• workbench_access
  7.x-1.2


• workbench_media
  7.x-1.1


• workbench_profile
  7.x-1.1


• xmlsitemap
  7.x-2.0-rc2

My site is
simple and don't have many visitors. I am talking about 500 visitors a day maybe. Drupal
can cause so much CPU loading? Or a
module?

Other problem is memory usage. When a
process is created, 80M is allocated for apache2. I think is too much.

My problem is that CPU
(all cores) have a high load. Most of time, hitting between 90% and 100% load! The
offending process is the apache2. Memory is also consumed without pity.
Of a 8GB total, the consumed memory is about 6.5GB to
7.5GB. I don't know if my apache configuration is wrong or if I'm really
need more hardware (I guess not). Drupal can cause high CPU
load?

When the CPU load hits 100%, the site goes
down and we have to restart apache. I did a workaround solution with Drupal using APC
and installing Boost. had some effectiveness, but CPU load still high. Very
high.

If you need more information, like Drupal
modules and PHP extensions. Please let me know.

class="post-text" itemprop="text">

class="normal">Answer

Other problem is memory usage. When a process is
created, 80M is allocated for apache2. I think is too
much.

Is
that real or virtual memory? Honestly, it's not very much; more to the point, you should
focus on fixing things that are causing problems, not just things that you "think"
should be different.

If you want Apache
processes to take up less memory, you should disable modules (as each one is more code
that needs to be in memory). But if you need all the modules you've got enabled, then,
well, that's that.

One approach I've used when
administrating a memory-constrained machine was to move certain tasks out of Apache and
into other servers, so I could tune them
separately.

But a far simpler approach is to
change

MaxClients
            120

to
something more reasonable for your
workload:

If we
consider the rewrite accesses and the main site traffic, we have about 70 requests per
minute. Right now, we have 33 incoming
connections.

I'll
get back to that momentarily, but if you're only dealing with 33 concurrent requests,
you don't need 120
workers!

MaxClients
            40

And you
should probably tune down MinSpareServers and
MaxSpareServer to something like 5 and 10, respectively.
There's no need to have 30 workers sitting around doing
nothing.

Now, getting back
to

If we consider
the rewrite accesses and the main site traffic, we have about 70 requests per minute.
Right now, we have 33 incoming
connections.

If
you've got 33 concurrent requests, but you're only doing 70 a minute, there are a couple
of possibilities:

1. Your
   requests are taking around 30 seconds each to serve!


2. Your
   request rate isn't very stable, and most of the minute you're doing
   nothing.

If #1 is the
case, I don't really know how to help - something is
incredibly wrong, so wrong I don't even know where to tell
you to start looking.

If it's #2, my guess is
you're serving all your static assets (images, js, css, fonts) from your server. It's
best to put these on a CDN, but if you really can't do that, you can set super-long
cache times on them and turn Varnish back on. If you're using Apache processes with PHP
and a whole host of other things just to serve static files, you're wasting resources -
do that with something
simpler!

My problem is that CPU (all cores) have a high load. Most of time, hitting
between 90% and 100% load! The offending process is the
apache2.

Is this a
constant number, or only when you're serving
requests?

How does disk I/O look
(iostat -mhx 2)? What is MySQL doing (show
processlist;)?

/>

Your server is vastly overpowered for
what you've described. This is good news, because it means you should be able to fix
this problem.