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I have a Parallel Plesk 11.0.0 with CentOS 6.3. Lately, I've noticed that my web server runs VERY slow (not the norm), CPU average at 80% no matter what kind of traffic, and my top is filled with these:

# top
top - 23:46:02 up 13:14,  1 user,  load average: 70.87, 68.98, 66.78
Tasks: 504 total,  77 running, 426 sleeping,   0 stopped,   1 zombie
Cpu(s): 76.7%us, 22.9%sy,  0.0%ni,  0.0%id,  0.0%wa,  0.0%hi,  0.3%si,  0.0%st
Mem:  16431960k total,  9584416k used,  6847544k free,   322880k buffers
Swap:  4194288k total,        0k used,  4194288k free,  3394184k cached

29794 mysql     10 -10 3418m 200m 6592 S 25.5  1.2  16:34.02 mysqld
11166 fstops    20   0  224m  46m 9776 R  8.0  0.3   0:00.27 php-cgi
11149 fstops    20   0  226m  48m 9804 R  7.6  0.3   0:00.30 php-cgi
 9917 fstops    20   0  241m  70m 7744 R  7.3  0.4   0:05.02 php-cgi
11143 fstops    20   0  240m  68m 7684 R  7.3  0.4   0:00.36 php-cgi
11152 fstops    20   0  226m  48m 9804 R  7.3  0.3   0:00.30 php-cgi
11160 fstops    20   0  225m  47m 9788 S  7.3  0.3   0:00.27 php-cgi
11167 fstops    20   0  223m  45m 9772 R  7.3  0.3   0:00.26 php-cgi
11169 fstops    20   0  222m  44m 9752 R  7.3  0.3   0:00.23 php-cgi
11172 fstops    20   0  221m  43m 9720 R  7.3  0.3   0:00.22 php-cgi
11155 fstops    20   0  227m  49m 9780 R  7.0  0.3   0:00.28 php-cgi
11157 fstops    20   0  226m  48m 9804 R  7.0  0.3   0:00.28 php-cgi
11159 fstops    20   0  226m  48m 9804 R  7.0  0.3   0:00.28 php-cgi
11170 fstops    20   0  222m  44m 9728 R  7.0  0.3   0:00.22 php-cgi

Will someone please help me troubleshoot the slowness? Thank you in advance, and please tell me what else I need to report.

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the load average is way over limit. did you check the apache logs if you are not beeing hit by a lot of requests? There is even some mysql load, so I am assuming there is actually some heavy page request (or at least heavy for your server... maybe provide a snippet of the apache log –  mlaug Jan 20 '13 at 0:42
I have a Wordpress site that gets around 200-300 visitors at any given moment. Nothing seems out of the norm in my logs. –  aZn137 Jan 21 '13 at 1:39

1 Answer 1

php-cgi is by its very nature substantially slower than mod-php. Are you getting more traffic than you used to? It is very possible that an increase in traffic can cause this.

I have very little experience with php-cgi. I would suggest replacing php-cgi with mod-php. Alternatively, if you wish to have security and isolation that comes with php-cgi, have a look at php-fastcgi.

EDIT: Reference for php-cgi being slower than mod-php

By default, PHP is built as both a CLI and CGI program, which can be used for CGI processing. If you are running a web server that PHP has module support for, you should generally go for that solution for performance reasons.

I am sure there were other references on the web including benchmarks but can't seem to find them anymore.

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No, my traffic is as usual, about 200-300 online users at any given moment (based on Google Analytics). –  aZn137 Jan 21 '13 at 1:33
If we look at your snapshot of top, your total cpu usage is at ~77%. mysql is at ~26%. The rest of the lines are php-cgi. Assuming this holds true for the rest of the processes, it seems that php-cgi is using ~51% of your cpu. This is far too high for a php app with 200-300 active users. consider changing from php-cgi and also take a look at solutions like apc (php.net/manual/en/book.apc.php) –  drone.ah Jan 21 '13 at 9:04
I turned off fastcgi and everything seems fine now; it's back to hovering at 20-40% CPU. Thanks guys. –  aZn137 Jan 22 '13 at 14:19
Glad to be of help. Unless its a db heavy website or a lower-spec server, the MySQL CPU usage may also be worth looking at. Maybe some indexes could help ;-) –  drone.ah Jan 23 '13 at 15:35
@drone.ah php-cgi is slower than mod-php? You had better explain yourself. Citation would be grand. –  Peter Dec 2 '14 at 9:05

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