I decided to change my OP to Nginx from Litespeed because i read much about the low resource that Nginx would cost.

Im running a Wordpress site with 500 users online

Okay thanks Guys for that much help :) I edited some things.

I have some questions left too:

Do i have to remove the ; before the pm. settings? I removed it What config counts? I got two fast cgi one in /etc/php5/fpm called php-fpm.conf and one in /etc/php5/fpm/pool.d called www.conf ?

I tried the new config over night and when i wake up i already got a blank page. Top:

top - 13:55:27 up 1 day, 19:28,  2 users,  load average: 0.18, 0.36, 0.19
Tasks:  84 total,   1 running,  83 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.2%us,  0.0%sy,  0.0%ni, 99.8%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:   3974264k total,  1051360k used,  2922904k free,   162380k buffers
Swap:  3998700k total,        0k used,  3998700k free,   609220k cached

 1857 www-data  20   0  193m  55m  22m S    0  1.4   0:04.67 php5-fpm
    1 root      20   0  8356  808  680 S    0  0.0   0:01.37 init
    2 root      20   0     0    0    0 S    0  0.0   0:00.00 kthreadd

I think cpu usage is now lower, but thats not fixing the crash...

My configs are now: php-fpm.conf

; FPM Configuration ;

; All relative paths in this configuration file are relative to PHP's install
; prefix (/usr). This prefix can be dynamicaly changed by using the
; '-p' argument from the command line.

; Include one or more files. If glob(3) exists, it is used to include a bunch of
; files from a glob(3) pattern. This directive can be used everywhere in the
; file.
; Relative path can also be used. They will be prefixed by:
;  - the global prefix if it's been set (-p arguement)
;  - /usr otherwise

; Global Options ;

; Pid file
; Note: the default prefix is /var
; Default Value: none
pid = /var/run/php5-fpm.pid

; Error log file
; If it's set to "syslog", log is sent to syslogd instead of being written
; in a local file.
; Note: the default prefix is /var
; Default Value: log/php-fpm.log
error_log = /var/log/php5-fpm.log

; syslog_facility is used to specify what type of program is logging the
; message. This lets syslogd specify that messages from different facilities
; will be handled differently.
; See syslog(3) for possible values (ex daemon equiv LOG_DAEMON)
; Default Value: daemon
;syslog.facility = daemon

; syslog_ident is prepended to every message. If you have multiple FPM
; instances running on the same server, you can change the default value
; which must suit common needs.
; Default Value: php-fpm
;syslog.ident = php-fpm

; Log level
; Possible Values: alert, error, warning, notice, debug
; Default Value: notice
;log_level = notice

; If this number of child processes exit with SIGSEGV or SIGBUS within the time
; interval set by emergency_restart_interval then FPM will restart. A value
; of '0' means 'Off'.
; Default Value: 0
emergency_restart_threshold = 1

; Interval of time used by emergency_restart_interval to determine when 
; a graceful restart will be initiated.  This can be useful to work around
; accidental corruptions in an accelerator's shared memory.
; Available Units: s(econds), m(inutes), h(ours), or d(ays)
; Default Unit: seconds
; Default Value: 0
emergency_restart_interval = 1s

; Time limit for child processes to wait for a reaction on signals from master.
; Available units: s(econds), m(inutes), h(ours), or d(ays)
; Default Unit: seconds
; Default Value: 0
process_control_timeout = 10s

; The maximum number of processes FPM will fork. This has been design to control
; the global number of processes when using dynamic PM within a lot of pools.
; Use it with caution.
; Note: A value of 0 indicates no limit
; Default Value: 0
process.max = 150

; Send FPM to background. Set to 'no' to keep FPM in foreground for debugging.
; Default Value: yes
;daemonize = yes

; Set open file descriptor rlimit for the master process.
; Default Value: system defined value
rlimit_files = 1024

; Set max core size rlimit for the master process.
; Possible Values: 'unlimited' or an integer greater or equal to 0
; Default Value: system defined value
;rlimit_core = 0

; Specify the event mechanism FPM will use. The following is available:
; - select     (any POSIX os)
; - poll       (any POSIX os)
; - epoll      (linux >= 2.5.44)
; - kqueue     (FreeBSD >= 4.1, OpenBSD >= 2.9, NetBSD >= 2.0)
; - /dev/poll  (Solaris >= 7)
; - port       (Solaris >= 10)
; Default Value: not set (auto detection)
; events.mechanism = epoll

; Pool Definitions ; 

; Multiple pools of child processes may be started with different listening
; ports and different management options.  The name of the pool will be
; used in logs and stats. There is no limitation on the number of pools which
; FPM can handle. Your system will tell you anyway :)

; To configure the pools it is recommended to have one .conf file per
; pool in the following directory:

request_terminate_timeout = 30s

pm.max_children = 25

; The number of child processes created on startup.
; Note: Used only when pm is set to 'dynamic'
; Default Value: min_spare_servers + (max_spare_servers - min_spare_servers) / 2
pm.start_servers = 5

; The desired minimum number of idle server processes.
; Note: Used only when pm is set to 'dynamic'
; Note: Mandatory when pm is set to 'dynamic'
pm.min_spare_servers = 2

; The desired maximum number of idle server processes.
; Note: Used only when pm is set to 'dynamic'
; Note: Mandatory when pm is set to 'dynamic'
pm.max_spare_servers = 5

; The number of seconds after which an idle process will be killed.
; Note: Used only when pm is set to 'ondemand'
; Default Value: 10s
pm.process_idle_timeout = 10s;


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_FILENAME     $request_filename;
fastcgi_param   SCRIPT_NAME     $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/$nginx_version;

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_param  HTTPS           $https;

# PHP only, required if PHP was built with --enable-force-cgi-redirect
fastcgi_param   REDIRECT_STATUS     200;

fastcgi_connect_timeout 60;
fastcgi_send_timeout 180;
fastcgi_read_timeout 180;
fastcgi_buffer_size 128k;
fastcgi_buffers 4 256k;
fastcgi_busy_buffers_size 256k;
fastcgi_temp_file_write_size 256k;
fastcgi_intercept_errors on;

nginx config:

user www-data;
worker_processes 2;
pid /var/run/nginx.pid;

events {
    worker_connections 500;
    # multi_accept on;

http {

    # Basic Settings

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 40;
    types_hash_max_size 2048;
    server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

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

    # Logging Settings

    # access_log /var/log/nginx/access.log;
    # error_log /var/log/nginx/error.log;

    # Gzip Settings

    gzip on;
    gzip_disable "msie6";

 gzip_vary on;
 gzip_proxied any;
 gzip_comp_level 9;
 gzip_buffers 16 8k;
 gzip_http_version 1.1;
 gzip_types text/plain text/css application/json application/x-javascript text/$


; Start a new pool named 'www'.
; the variable $pool can we used in any directive and will be replaced by the
; pool name ('www' here)

user = www-data
group = www-data

pm = dynamic

pm.max_children = 25

pm.start_servers = 5

pm.min_spare_servers = 2

pm.max_spare_servers = 5

pm.process_idle_timeout = 10s;

pm.max_requests = 100

request_terminate_timeout = 120s

The Mashine: Dualcore 4gb ram

  • What does the PHP-FPM error log say? – devicenull Apr 3 '12 at 22:38
  • Theres only the record about when i restart the fpm some other...[04-Apr-2012 13:46:44] NOTICE: Terminating ... [04-Apr-2012 13:46:44] NOTICE: exiting, bye-bye! [04-Apr-2012 13:46:44] NOTICE: fpm is running, pid 1744 [04-Apr-2012 13:46:44] NOTICE: ready to handle connections [04-Apr-2012 13:48:57] NOTICE: [pool www] child 1748 exited with code 0 after 132.647614 seconds from start [04-Apr-2012 13:48:57] NOTICE: [pool www] child 1829 started – chillah Apr 4 '12 at 11:20
  • I just noticed that php fpm crashes faster if i disable/enable or edit my wordpress files. But im not 100% sure... – chillah Apr 5 '12 at 0:56
  • Are you still getting the crashes? Did you checked usage of APC? Usually you define a pool in a separate config file (where all your pm settings go). – Dada Apr 5 '12 at 13:14
  • Yes it still crashes. The crashes seems to increase with more visitors on my page. I dont see the apc prozess in "top". How can i check it? I used cron to restart php fpm every 2 minutes for now.... I realy need to fix that problem soon! – chillah Apr 5 '12 at 16:01

It is not clear whether you are using any opcode cacher like APC. First of all, make it enabled. Adjust its the memory to avoid fragmentation. Also, use socket, not http connection from nginx to php5-fpm, and place that socket on /dev/shm. In nginx, use fastcgi_pass unix:/dev/shm/php5-fpm.sock;, and change php5-fpm's config accordingly.

Try to lower pm.max_children to something more realistic like 30-40-50-60 and see the load and free memory with free -m. See if clients getting any 502/504 errors. Lower pm.start_servers, min and max_spare accordingly (15, 5, 25).

If there is a lot of anonymous users, consider to use any caching plugin for wordpress like WP-FFPC, WP Super Cache or similar.

Disable gzipping if you have it enabled in nginx.

Perhaps you need to adjust fastcgi_buffer_size and fastcgi_buffers options in nginx.

Check if you have Query cache enabled and sufficient on Mysql.

Have monitoring system like munin installed on the site in order to check load/memory consumption/latency etc.

  • The connection between nginx and php5-fpm may not be HTTP but just TCP. JFYI. – Aykut Çevik Jan 26 '15 at 12:39

Your server is likely to suffers when it rans out of memory to run php processes. Your php5-fpm settings seem to be too generous for 4GB RAM. I've had lots of fiddling to arrive at optimal php5-fpm configs (for 32GB ram and +1K online users, here are my relevant params:

pm.max_children = 25
pm.start_servers = 5
pm.min_spare_servers = 2 
pm.max_spare_servers = 5
pm.max_requests = 100

Also don't forget to set a request termination timeout to avoid memory shortage due to idle processes:

request_terminate_timeout = 120s

Whatever timout you use in the above directie should be in accordance with max_execution_time directive in your php.ini.

As for nginx,having gzip on is a very good idea: It is very cheap CPU-wise and saves your server loads of bandwidth.

   #sendfile on;
    #tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 10;
    types_hash_max_size 2048;
    # server_tokens off;
    gzip on;
    gzip_disable "msie6";

    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 9;
    gzip_buffers 16 8k;
    gzip_http_version 1.1;
    gzip_types text/plain text/css application/json application/x-javascript text/$

Good luck

  • I tried your config over night, the cpu seems usage seems to be lower now hovewer that didnt fixed the blank pages and the crashes. Heres a Ip counter Image: abload.de/img/unbenanntsgyxi.png – chillah Apr 4 '12 at 11:16
  • I agree with the recommendation to set request_terminate_timeout, but your reason is not correct ;) This directive is to kill a running process after a certain amount of CPU time, as a safeguard when PHP's max_execution_time could not (which should have a bit smaller value to get the first chance) [source]. "To avoid memory shortage due to idle processes", the directive to use is pm.process_idle_timeout = 40 [see this answer]. – tanius Jan 30 '15 at 22:48

I would suggest to use pm = ondemand, and make sure the size of the memory_limit in php is sizable to the memory of the machine.

For a 4GB machine with 128 MB in PHP process that would be around ~ 24 PHP-FPM servers you can have running, ondemand is nice as the server would determine that maximum amount of servers and create new as the load goes up.

  • 1
    Agree that the PHP-FPM ondemand process manager is the better choice in most cases. But its max. number of child processes cannot be calculated like this: memory_limit is the absolute max that a PHP process may consume before forcefully terminated. On average, they consume much less. – tanius Jan 30 '15 at 23:03
  • 1
    And anyway, memory is usually not the limiting factor for max. children, rather CPU cores. Max. child count should be set to approx. CPU core count, plus a few to compensate for IO waits etc.. Nothing goes faster beyond 100% CPU load, it's just a difference between waiting in queue and slow parallel serving with switching. – tanius Jan 30 '15 at 23:05

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