nginx makes mysqld die all the time

[M. Fioretti]

On 2015-08-18 14:36, Steve Wilson wrote:
> Hi,
> 
> When I migrated from apache+mod_php to nginx+php-fpm I found I had a
> few websites using persistent mysql connections which never closed.

Steve, thanks for this tip. This surely was part of the problem, but
not all of it.

Sure enough, when I first noticed this problem, I also found in dmesg
messages like this:

Out of memory: kill process 31066 (mysqld) score 30155 or a child
Killed process 31066 (mysqld)

yesterday, as soon as I was able to ssh again, I turned

mysql.allow_persistent = Off in php.ini (it was On)

and restarted everything. Page load time decreased noticeably AND there
where no more mysql crashes for the rest of the day.
This morning, however, I found mysql died again with the same symptom
(dead but subsystem locked) and a DIFFERENT message in dmesg, that I
had never seen before:

Out of memory: kill process 13812 (php-fpm) score 18223 or a child
Killed process 13812 (php-fpm)

the nginx and php-fpm configuration files are pasted below (I have 
several virtual
hosts all configured that way for wordpress, plus one drupal and one 
semantic scuttle
site, if it matters). What next? Any help is welcome!

Marco

[root at fima ~]# more /etc/nginx/nginx.conf

user              nginx;
worker_processes  1;

error_log  /var/log/nginx/error.log;
#error_log  /var/log/nginx/error.log  notice;
#error_log  /var/log/nginx/error.log  info;

pid        /var/run/nginx.pid;


events {
     worker_connections  1024;
}

http {
     include       /etc/nginx/mime.types;
     default_type  application/octet-stream;

     server_names_hash_bucket_size  64;
     server_tokens off;
     access_log  /var/log/nginx/access.log combined  buffer=32k;
     log_format    '$remote_addr - $remote_user [$time_local] $status '
                       '"$request" $body_bytes_sent "$http_referer" '
                       '"$http_user_agent" "$http_x_forwarded_for"';

     sendfile        on;
     #tcp_nopush     on;

     #keepalive_timeout  0;
     keepalive_timeout  65;

     #gzip  on;

     # Load config files from the /etc/nginx/conf.d directory
     # The default server is in conf.d/default.conf
     include /etc/nginx/conf.d/*.conf;

}

and this is configuration for one of the wordpress sites, I only changed
the domain name. The configuration is due to the fact that, for several
reasons out of my control, I **must** run two fully independent 
wordpress
installations, but "nested" into each other, that is:

myblog.example.com/   (english blog, by wordpress installed in 
$documentroot/myblog)
myblog.example.com/it (italian version, by separate wordpress installed 
in $documentroot/myblog_it)

the above worked fine with apache. Can the equivalent config for
nginx be related to the problem I'm seeing? If yes, how, and how to
fix it? And while we are at this: advice on anything else I could 
optimize is
also very welcome of course, even if not related to the main problem.


[root at fima ~]# more /etc/nginx/conf.d/stop.conf

server {
        listen       80;
        server_name  myblog.example.com;
        root         /var/www/html/wordpress/;
        include      /etc/nginx/default.d/*.conf;

        # configuration for the italian version, installed
        # in root/myblog_it, but having as url example.com/stop/it

        location ^~ /it/ {
               	rewrite ^/it/(.+) /myblog_it/$1 ;
        	      	index             /myblog_it/index.php;
        }

        location /myblog_it/ {
        		try_files $uri $uri/ /myblog_it/index.php?args;
		index index.php;
		location ~ \.php$ {
			 fastcgi_pass unix:/tmp/phpfpm.sock;
			 fastcgi_index  index.php;
			 fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
			 include        fastcgi_params;
			 }
		}

##################################################################
# main blog

         location ^~ / {
                  rewrite ^/(.+) /myblog/$1 ;
                  index          /myblog/index.php;
		 }

	location /myblog/ {
		 try_files /$uri /$uri/ /myblog/index.php?args;
     	 	 index                        index.php;
		 }

	location ~ \.php$ {
         	 fastcgi_pass unix:/tmp/phpfpm.sock;
                  fastcgi_index  index.php;
                  fastcgi_param  SCRIPT_FILENAME  
$document_root/$fastcgi_script_name;
                  include        fastcgi_params;
       	 	}
}


php-fpm configuration:

[root ~]# grep -v '^;' /etc/php-fpm.conf | uniq

include=/etc/php-fpm.d/*.conf

[global]
pid = /var/run/php-fpm/php-fpm.pid

error_log = /var/log/php-fpm/error.log

daemonize = no

emergency_restart_threshold = 10
emergency_restart_interval = 1m
process_control_timeout = 10s

AND ALSO:

[root ~]# grep -v '^;' /etc/php-fpm.d/www.conf | uniq
[www]


listen.allowed_clients = 127.0.0.1

listen = /tmp/phpfpm.sock
listen.owner = nginx
listen.group = nginx
user = nginx
group = nginx

pm = dynamic

pm.max_children = 50

pm.start_servers = 5

pm.min_spare_servers = 5

pm.max_spare_servers = 35





slowlog = /var/log/php-fpm/www-slow.log


php_admin_value[error_log] = /var/log/php-fpm/www-error.log
php_admin_flag[log_errors] = on

php_value[session.save_handler] = files
php_value[session.save_path] = /var/lib/php/session