CPU Load 100%

muj

When I stress the my server for 10s the php-fpm goes to 100% and stays even when I stop. To recover I have to restart php-fpm then it goes normal.

Any ideas on how to fix this high load after stress?

perennate

How long does it say? Even after PHP script timeout?

muj

Dunno, I quickly restart. But it would stay long if I leave it.

super320

Please check your codes at first I think

muj

Which code?

I run Nginx.

muj

Should I reinstall PHP-FPM?

muj

Here is the htop: http://i.imgur.com/IZaT1RW.png

muj

PHP5-FPM Log: http://pastebin.com/PV8vgsEx

udk

try again with a really simple php script, just an echo or something

that way you can tell if it's your code that's the problem

muj

@udk said:
try again with a really simple php script, just an echo or something

that way you can tell if it's your code that's the problem

But I have all my files WordPress, this hasn't happened before, just when I reinstalled the server.

tchen

You're exhausting your child processes (pm.max_children) during the stress test and are queuing up the requests. Increase it if you've got memory to spare, otherwise you just have to be patient and let it drain the pipe.

muj

@tchen said:
You're exhausting your child processes (pm.max_children) during the stress test and are queuing up the requests. Increase it if you've got memory to spare, otherwise you just have to be patient and let it drain the pipe.

Ok, but the CPU just stays around 100% and I can't access the website.

sman

switch to apache

budingyun

What Linux distribution do you use?

muj

@budingyun said:
What Linux distribution do you use?

Debian 6 32bit

muj

@sman said:
switch to apache

Should I?, I'm sure it needs more resources and there are security issues?

budingyun

@muj said:
Debian 6 32bit

Please share your php5-fpm configuration.

nano /etc/php5/fpm/pool.d/www.conf

This is my low end configuration btw:

[www] user = www-data group = www-data listen = 127.0.0.1:9000; pm = dynamic pm.max_children = 1 pm.start_servers = 1 pm.min_spare_servers = 1 pm.max_spare_servers = 1 pm.max_requests = 128

muj

@budingyun said:
pm.max_requests = 128`

[www]
user = www-data
group = www-data
listen = /var/run/php5-fpm.sock
pm = ondemand
pm.max_children = 5
pm.start_servers = 1
pm.min_spare_servers = 1
pm.max_spare_servers = 1
pm.process_idle_timeout = 3s;
pm.max_requests = 500
chdir = /var/www/
env[HOSTNAME] = $HOSTNAME
php_admin_value[upload_max_filesize] = 32M

budingyun

Try changing it to dynamic.

pm = ondemand -> pm = dynamic

or increase pm.process_idle_timeout value maybe to 10 seconds.

muj

@budingyun said:
Try changing it to dynamic.

pm = ondemand -> pm = dynamic

or increase pm.process_idle_timeout value maybe to 10 seconds.

Added ondemand and dynamic and restarted php-fpm.
I stress it goes to 100% and stays even though I stop the stress.

budingyun

Something like this?

[www]
user = www-data
group = www-data
listen = /var/run/php5-fpm.sock
pm = dynamic
pm.max_children = 4
pm.start_servers = 1
pm.min_spare_servers = 1
pm.max_spare_servers = 1
pm.max_requests = 500
chdir = /var/www/
env[HOSTNAME] = $HOSTNAME
php_admin_value[upload_max_filesize] = 32M

muj

@budingyun said:
Something like this?

Yep I did that.

[www]
user = www-data
group = www-data
listen = /var/run/php5-fpm.sock
pm = dynamic
pm.max_children = 5
pm.start_servers = 1
pm.min_spare_servers = 1
pm.max_spare_servers = 1
pm.process_idle_timeout = 10s;
pm.max_requests = 500
chdir = /var/www/
env[HOSTNAME] = $HOSTNAME
php_admin_value[upload_max_filesize] = 32M

tchen

What do you use for stress testing? ab? How many requests/sec are you simulating? Be reasonable.

Anyways, it comes down to the fact that your wordpress pages are slow enough that they're causing back pressure on php-fpm. With only 5 child processes, a standard ab test will saturate the pipeline. Even if you stop ab, those requests are in the queue on the server and will have to be worked through hence why you keep seeing 100% cpu even when you 'stop' the test.

To figure out what a good php-fpm setting, you'll have to revisit how much load you expect first. Once you figure that out, then you can raise max_children so that it can satisfy those requests while not running out of memory.

Useful link:
http://myshell.co.uk/index.php/adjusting-child-processes-for-php-fpm-nginx/

muj

@tchen said:
What do you use for stress testing? ab? How many requests/sec are you simulating? Be reasonable.

Anyways, it comes down to the fact that your wordpress pages are slow enough that they're causing back pressure on php-fpm. With only 5 child processes, a standard ab test will saturate the pipeline. Even if you stop ab, those requests are in the queue on the server and will have to be worked through hence why you keep seeing 100% cpu even when you 'stop' the test.

To figure out what a good php-fpm setting, you'll have to revisit how much load you expect first. Once you figure that out, then you can raise max_children so that it can satisfy those requests while not running out of memory.

Useful link:
http://myshell.co.uk/index.php/adjusting-child-processes-for-php-fpm-nginx/

LOIC, 20 threads. Even when I do it for 3 seconds it goes 100%

BrianHarrison

Why not drop PHP-FPM? There are plenty other more actively developed and better maintained solutions and mediation strategies for high-traffic websites than PHP-FPM.

Rallias

@BrianHarrison said:
Why not drop PHP-FPM? There are plenty other more actively developed and better maintained solutions and mediation strategies for high-traffic websites than PHP-FPM.

You mean you're suggesting something be used other than what's in PHP core?

muj

@BrianHarrison said:
Why not drop PHP-FPM? There are plenty other more actively developed and better maintained solutions and mediation strategies for high-traffic websites than PHP-FPM.

Could you name some please?

Rallias

@muj said:
Could you name some please?

Try adding the ReallyStatic plugin to your blog. There's no way in fuck you're going to squeeze performance out of wordpress.

muj

@Rallias said:
Try adding the ReallyStatic plugin to your blog. There's no way in fuck you're going to squeeze performance out of wordpress.

Do you think I should reinstall PHP-FPM?

Rallias

@muj said:
Do you think I should reinstall PHP-FPM?

Keep PHP-FPM for now. There's NOTHING BETTER for executing PHP.

And yes, I'm aware that is a very low standard.

budingyun

@muj said:
Do you think I should reinstall PHP-FPM?

How about your nginx configuration?