What is wrong in my php-fpm configuration?
I have a 64-bit server but only 256MB of RAM. So, I moved to nginx server with fast-cgi to connect to PHP. I have PHP 5.3.6 running.
The issue is that after every two or three days when I try to access any PHP page then I get server internal error. The only way around is to restart php-fpm manually. This means I should have set some wrong parameters which is causing it to choke. Below I have listed the relevant configs.
/etc/php-fpm.conf :-
include=/etc/php-fpm.d/*.conf
log_level = error
;emergency_restart_threshold = 0
;emergency_restart_interval = 0
;process_control_timeout = 0
/etc/php-fpm.d/www.conf :-
[www]
pm = dynamic
pm.max_children = 10
pm.start_servers = 3
pm.min_spare_servers = 2
pm.max_spare_servers = 5
pm.max_requests = 500
/etc/nginx/php.conf :-
location ~ .php {
fastcgi_param QUERY_STRING $query_string;
fastcgi_param REQUEST_METHOD $request_method;
fastcgi_param CONTENT_TYPE $content_type;
fastcgi_param CONTENT_LENGTH $content_length; fastcgi_param SCRIPT_NAME $fastcgi_script_name;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_param REQUEST_URI $request_uri;
fastcgi_param DOCUMENT_URI $document_uri;
fastcgi_param DOCUMENT_ROOT $document_root;
fastcgi_param SERVER_PROTOCOL $server_protocol; fastcgi_param GATEWAY_INTERFACE CGI/1.1;
fastcgi_param SERVER_SOFTWARE nginx; fastcgi_param REMOTE_ADDR $remote_addr;
fastcgi_param REMOTE_PORT $remote_port;
fastcgi_param SERVER_ADDR $server_addr;
fastcgi_param SERVER_PORT $server_port;
fastcgi_param SERVER_NAME $server_name; fastcgi_pass unix:---some-location---;
}
Update 1
And I have four nginx processes running. On an average each php-fpm process takes 35MB of RAM (Virtual memory size 320MB each). I also have a MySql process running.
Update 2
I forgot to paste the logs.
php-fpm error log :-
WARNING: [pool www] seems busy (you may need to increase start_servers, or min/max_spare_servers), spawning 8 children, there are 1 idle, and 7 total children
WARNING: [pool www] server reached max_children setting (10), consider raising it
NOTICE: Terminating ...
php-fpm www.error log :-
PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 122880 bytes) in /home/webadmin/blog.applegrew.com/html/wordpress/wp-content/plugins/jetpack/class.jetpack-signature.php on line 137
PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 122880 bytes) in /home/webadmin/blog.applegrew.com/html/wordpress/wp-content/plugins/jetpack/class.jetpack-signature.php on line 137
PHP Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 122880 bytes) in /home/webadmin/blog.applegrew.com/html/wordpress/wp-content/plugins/jetpack/class.jetpack-signature.php on line 137
An off-hand recommendation would be to lower your set values – probably cut them in half.
You have: pm.max_children = 10
If you say 35MB/process = 350MB; on a 256MB box that means either a lot of swapping or you run out of memory – neither is good.
I’d say take at least 100MB for other processes, maybe even 150MB to be safe, and then divide that number by 35MB to get your max_children. Keep all other numbers in line:
pm = dynamic
pm.max_children = 4
pm.start_servers = 1
pm.min_spare_servers = 1
pm.max_spare_servers = 2
pm.max_requests = 500
Stop PHP-FPM and run free to get an idea of your available memory – divide by your 35MB to get your max_children.
Depending on how much memory MySQL takes, you might have to drop max_children to 3.
I do find that PHP-FPM processes share a lot of memory, do a quick experiment to determine how much is really used. Stop PHP-FPM and run free. Start PHP-FPM visit a few common pages (necessary since memory increases depending on the pages loaded), and check the total memory used, again using free – divide the difference by the number of processes. It isn’t a perfect system, but I do find it to be fairly accurate (sometimes the data column in top isn’t bad either).
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