# Optimizing worker\_processes, worker\_connections & PHP\_FCGI\_CHILDREN - Any Good Tutorial? **URL:** \ **Category:** NGINX\ **Created:** [June 17, 2010, 4:22pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218 "2010-06-17T16:22:23Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:22pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/1 "2010-06-17T16:22:23Z")
First - all my servers are running fine. Thanks a ton to nginx! Lately, I have been brainstorming a lot on 3 configuration variables to squeeze maximum performance that I can get from my hardware. 3 variables of my interest are: [list=1] [_] worker\_processes [_] worker\_connections [\*] PHP\_FCGI\_CHILDREN [/list] I searched extensively on Google, mailing lists, wiki, etc but till date couldn’t find any robust guide as on how these affects performance and other aspects of my webserver/webapp. As I am aiming for very-very high traffic configuration, I will first move all images/js/css load to CDN. So my nginx will be mostly busy in dealing PHP stuff. [list] [_] So will it make more sense to increase PHP\_FCGI\_CHILDREN or worker\_processes? [_] Is it good to make PHP\_FCGI\_CHILDREN = 1 if I am using APC for PHP opcode caching? [/list] If I want to achieve number of 100,000, then what is difference between following arithmetic: [list] [_] 10 worker\_processes \* 10,000 worker\_connections \* 1 PHP\_FCGI\_CHILDREN [_] 10 worker\_processes \* 1,000 worker\_connections \* 10 PHP\_FCGI\_CHILDREN [_] 10 worker\_processes \* 100 worker\_connections \* 100 PHP\_FCGI\_CHILDREN [_] 1 worker\_processes \* 1000 worker\_connections \* 100 PHP\_FCGI\_CHILDREN [\*] 1 worker\_processes \* 100,000 worker\_connections \* 1 PHP\_FCGI\_CHILDREN [/list] I know this arithmetic is not straight-forward as 3 variable controls 3 different aspects. But how does they impact each other? How amount of RAM, traffic pattern, PHP/non-PHP traffic ratio affects them? In short, what are all parameters I must consider? Sorry if some of my questions sounds lame. But I really wants to dig deeper into nginx config for high traffic load. Also if you think I am totally going in wrong direction, please feel free to correct me. Thanks, -Rahul Posted at Nginx Forum: > **[Optimizing worker\_processes, worker\_connections & PHP\_FCGI\_CHILDREN - Any...](https://forum.nginx.org/read.php?2,98498,98498#msg-98498)** > > First - all my servers are running fine. Thanks a ton to nginx! Lately, I have been brainstorming a lot on 3 configuration variables to squeeze maximum performance that I can get from my hardware. \[b\]3 variables of my interest are:\[/b\] \[list=1\] \[\*\]... ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:22pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/2 "2010-06-17T16:22:45Z")
> [\*] Is it good to make PHP\_FCGI\_CHILDREN = 1 if I am using APC > for PHP opcode caching? No. One child won’t do anything good on a multicore box (giving the usuall nature of php scripts - waiting on external resources like DBs etc). Nor it can saturate single cpu (also APC doesnt limit you here in any way). I would suggest to give it a try to the new FPM sapi/manager which is now included also in 5.3.x core. It gives you the ability to dynamically manage a pool of php processes (spawn more php childs if the server gets loaded or kill the unneeded spares). That way you dont need to control any settings from the webservers side. > **[Home - PHP-FPM](https://php-fpm.org/)** > **[Download - PHP-FPM](https://php-fpm.org/download/)** rr ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:27pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/3 "2010-06-17T16:27:00Z")
Thanks Reinis. Regarding… > > [\*] Is it good to make PHP\_FCGI\_CHILDREN = 1 if I am using APC > > for PHP opcode caching? > No. I read somewhere that 2 PHP processes do not share APC cache. So if I have 10 PHP\_FCGI\_CHILDREN - that means 10 times cache size. On > I would suggest to give it a try to the new FPM sapi/manager which is now included also in 5.3.x core. I do not use FPM and I really wonder why it is used? We can directly use php-fastcgi as mentioned here [http://tomasz.sterna.tv/2009/04/php-fastcgi-with-nginx-on-ubuntu/](http://tomasz.sterna.tv/2009/04/php-fastcgi-with-nginx-on-ubuntu/) Thanks for your time buddy. If you have more inputs, please share. -Rahul ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:34pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/4 "2010-06-17T16:34:41Z")
php-fpm is an actual management daemon, as opposed to using spawn-fcgi which you are still responsible for controlling. If you’re doing the spawn-fcgi route you might as well just use php-cgi -b and use upstart or some other controlling daemon and just do it yourself. spawn-fcgi doesn’t give you anything special AFAIK. Rasmus himself uses PHP-FPM now and gave it basically a thumbs up (in person) and nginx for [wepay.com](http://wepay.com) (the company he works for now) You don’t get much better clout than that. ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:34pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/5 "2010-06-17T16:34:41Z")
> php-fpm is an actual management daemon… > Thanks for details regarding PHP-FPM When I bumped into it first time, I thought its overhead - more like some people using lighthppd for running PHP on nginx. I will definitely try it but I still looking for equation to set numbers like worker\_processes, worker\_connections & PHP\_FCGI\_CHILDREN (or PHP\_FPM counterpart) perfectly. ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:27pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/6 "2010-06-17T16:27:03Z")
> I read somewhere that 2 PHP processes do not share APC cache. So if I > have 10 PHP\_FCGI\_CHILDREN - that means 10 times cache size. That could be true if the php processes are spawned seperatly (by webserver) each time a client request comes in - which is slow as hell (and somewhat mimics the apache forking mechanism). ## The preferred way (especially for high concurrency) is to spawn the php as permanent process and the webserver (nginx) talks to it through fastcgi ( [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/NginxHttpFcgiModule) ) - (you just provide ip:port which gives you also the ability if needed to use multiple boxes) that way all the php processes have the same APC opcode cache / shared memory (and there is no need to recompile script each time a new child is spawned). Not to mention other benefits like persistant connections (to memcache / db / etc) which aren’t killed each time a request finishes but reused on next. spawn-fcgi was kinda early way to do this (came from lighttpd) but now the inbuilt FPM sapi has much more control and options (like to kill processes which run for too long / monitor/backtrace the code) to miss the opportunity to try it out. rr ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:34pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/7 "2010-06-17T16:34:41Z")
Thanks Reinis for your time and valuable info. > The preferred way (especially for high concurrency) is to spawn the php as permanent process and > the webserver (nginx) talks to it through fastcgi ( [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/NginxHttpFcgiModule) ) I have setup my nginx as mentioned here - > **[GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki...](https://github.com/nginxinc/nginx-wiki)** > > ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com And I guess for this reason my APC cache is working fine! 🙂 > spawn-fcgi was kinda early way to do this (came from lighttpd) but now the inbuilt FPM sapi has much more control and options … I am really convinced about PHP-FPM and will definitely give it a try. Specially “upstream” stuff. > The basic approach usually as far as I know is to set worker\_processes based on your CPU core count … > In VPS, even with linode/slichost company, you see 4 cores when you > cat /proc/cpuinfo > But as its VPS and not PS, cores may be shared by some unknown fellows. > Do u still think, keeping core\_count math still helps? > So in short - both of the software products are clever enough to tell you what could be the optimal setting for you based on the workload of the box. > Agree. Switching to nginx was one of my best decision. > Fellow bloggers envy my servers uptime and speed and the fact is I pay > less in terms of hosting bill 😉 > remember also to tweak other system settings - like maximum open file descriptors, tcp port range etc > I will check this out. Looks like I never traveled in this direction. Thanks again Reinis. -Rahul ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:35pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/8 "2010-06-17T16:35:21Z")
On Tue, Jun 15, 2010 at 12:37 PM, Rahul B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I have setup my nginx as mentioned here - > [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/NginxHttpFcgiModule) > And I guess for this reason my APC cache is working fine! 🙂 I believe (and from what I see and hear) the APC cache is shared by all children from the parent. So each pool can share. I don’t think APC is global cross all pools however it might be, because when I do apc\_info() or whatever the function is, I see other people’s files (in different pools) in my file cache. ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:35pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/9 "2010-06-17T16:35:21Z")
@Michael Thanks again for heads up on PHP-FPM I am reading your post - [http://michaelshadle.com/2010/05/21/php-fpm-and-nginx-upstart-scripts/](http://michaelshadle.com/2010/05/21/php-fpm-and-nginx-upstart-scripts/) I hope to see our server using PHP-FPM next month (with ubuntu 10 +wordpress 3) -Rahul ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:35pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/10 "2010-06-17T16:35:21Z")
> I will definitely try it but I still looking for equation to set numbers > like worker\_processes, worker\_connections & PHP\_FCGI\_CHILDREN (or PHP\_FPM > counterpart) perfectly. The basic approach usually as far as I know is to set worker\_processes based on your CPU core count (either identical or sometimes there is benefit setting with some multiplier - 2\*cores (I have seen some improvements when using nginx as on-the-fly image resizer to utilise the box more)). worker\_connection - typical 1024 or 2048 usually is enough. Bassically the math is based on max\_clients where: max\_clients = worker\_processes \* worker\_connections Anyways nginx should complain in error log if the settings are too low and all the workers are exausted (like you have thousands of keepalive/active connections). The same with FPM - the basic settings which come with the sample config should be enough. If you leave the default notice error level log FPM should tell you if all of the php pool is fully used and there is a need to increase the setting. So in short - both of the software products are clever enough to tell you what could be the optimal setting for you based on the workload of the box. p.s. remember also to tweak other system settings - like maximum open file descriptors, tcp port range etc rr ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:51pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/11 "2010-06-17T16:51:47Z")
> So each pool can share. I don’t think APC is global cross all pools > however it might be, because when I do apc\_info() or whatever the > function is, I see other people’s files (in different pools) in my > file cache. In my case my VPS is hosting few domains with single user www-data. PHP, webroot, files all are owned as well as forked by this single user. I guess u mean apc.shm\_segments by pools? I have declared 4 pools but apc.php is saying… Shared Memory = 1 Segment(s) with 60.0 MBytes (mmap memory, pthread mutex locking) U can see my apc stats here - [http://devilsworkshop.org/apc.php](http://devilsworkshop.org/apc.php) I hope there is harm in making cache stats public! 😉 -Rahul ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:51pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/12 "2010-06-17T16:51:11Z")
2010/6/15 Reinis R. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > math is based on max\_clients where: max\_clients = worker\_processes \* > worker\_connections this is right only if your webserver is ONLY serving dynamic content without caching. If nginx is serving static file or dynamic content from cache, you will have less connections to the fcgi backend than you have incoming connections on the web server. There is no way to know exactly how many fcgi concurent connexions. You can set max\_children depending on your RAM. If you have 2Go of RAM, you’ll want to keep a part of this memory for system caching (let say 500 Mo). You’ll keep some for the system and the others apps (nginx) (let say 256Mo). It’ll stay a bit more than 1Go of RAM dedicated to fcgi. Depending on what your scripts are doing, you can imagine a memory size for one fcgi process and you can then deduce the max\_children. If you think your PHP process won’t consume more than 20Mo, you can set max\_children to 1256 (Mo) / 20 (Mo) =~ 62. But it’s all depending on what your application is doing, how the audition is surfing the website, you system, … ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 4:51pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/13 "2010-06-17T16:51:48Z")
Hi jerome. With your additional inputs, Can I safely set following rules for personal use? Of course, any configuration needs monitoring/tweaking. But I think its better to start with a base config which will be closer to the optimal config. \*Now for… worker\_connections \*1024/2048 are safe values. So its better if I leave them untouched. _worker\_processes_ Number of CPU core or its multiplier (assuming u have dynamic application with decent caching) More process ==\>\> Less Dynamic and Lower PHP\_FCGI\_CHILDREN Less Process ==\>\> More Dynamic and Higher PHP\_FCGI\_CHILDREN \*PHP\_FCGI\_CHILDREN \*Using TOP command and looking at RES memory value. Finding memory required by single instance of PHP. (in my case its 40MB and VIRT is 100MB!) Then doing arithmetic like: [Available RAM] = (Actual RAM) - (100 M or more OS + 200 M for DB + 16M for nginx (I have 8 worker\_process with 2MB memory for each )) Then, PHP\_FCGI\_CHILDREN = [Available RAM] / Single PHP instances’ memory requirement Sorry for trying to get mechanical here. But I already started to have better insight into all configuration variables I was curious at. Also are these numbers in anyway gets affected by fastcgi\_cache - [http://wiki.nginx.org/NginxHttpFcgiModule#fastcgi\_cache](http://wiki.nginx.org/NginxHttpFcgiModule#fastcgi_cache) Does fastcgi\_cache reduces load on fascgi-php ? ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 5:23pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/14 "2010-06-17T17:23:26Z")
> > worker\_connections > > this is right only if your webserver is ONLY serving dynamic content > without caching. If nginx is serving static file or dynamic content > from cache, you will have less connections to the fcgi backend than > you have incoming connections on the web server. There is no way to > know exactly how many fcgi concurent connexions. You can set > max\_children depending on your RAM. Nginx has a quite small memory footprint (if you dont go overboard with buffers per connection). And you can have thousands of open connections because of effective event models (especially when using it for comet-type applications) and still not consuming much memory. For nginx-type server maximum clients doesnt mean the same as for apache MaxClients which could result in the same number as httpd processes running (each with php module loaded) consuming loads of memory so you had to be extra carefull with that setting otherways things could turn ugly. The beauty about php in fastcgi mode is the controlled memory consumption (besides the typical leaking in php/extensions - which is “fixed” by periodically restarting the childs (done by the master php process)) - it doesnt really change/jump - eg you set 10 startup childs which easily can handle more than just 10 users as nginx makes a queue and will pass the requests to the php fcgi backend (of course if you are running php code like \ then only 10 clients at time (minute) will be processed for dynamic content). In short max\_clients/worker\_connections are only loosely related (it doesnt matter if thats a static or dynamic request - all go into the same worker threads (there is a bit difference if you make a lot of backend connections/proxying)) to amount of php processes in a world of nginx-type servers. And in case you use FPM even the variable PHP\_FCGI\_CHILDREN has become deprecated as the new syntax for process management is something like: pm = dynamic pm.max\_children = 70 pm.start\_servers = 20 pm.min\_spare\_servers = 5 pm.max\_spare\_servers = 20 pm.max\_requests = 1000 p.s. afaik the only thing which the php-dev team havent still implemented is the FCGI\_OVERLOADED (according to fcgi spec) feature.. to let the webserver know sooner that there aren’t enough resources on the backend to process the request rather than after timeouts. rr ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 5:23pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/15 "2010-06-17T17:23:26Z")
2010/6/15 Rahul B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > 1024/2048 are safe values. So its better if I leave them untouched. > depends on your visitors load. You can go higher than that if needed. > But I don’t think it’s you case > worker\_processes > Number of CPU core or its multiplier (assuming u have dynamic application > with decent caching) > More process ==\>\> Less Dynamic and Lower PHP\_FCGI\_CHILDREN > Less Process ==\>\> More Dynamic and Higher PHP\_FCGI\_CHILDREN worker\_process = num of CPU. nothing more > requirement > you can save more of OS as there is file caching which is usefull > Sorry for trying to get mechanical here. it’s a good start, then you’ll tweak > But I already started to have better insight into all configuration > variables I was curious at. > > Also are these numbers in anyway gets affected by fastcgi\_cache - > [GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/NginxHttpFcgiModule#fastcgi_cache) > Does fastcgi\_cache reduces load on fascgi-php ? Oh hell yes ! a dynamic content nginx is serving from cache won’t generate any load on the fcgi side as it won’t go there ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 5:24pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/16 "2010-06-17T17:24:02Z")
@ Reinis > And in case you use FPM even the variable PHP\_FCGI\_CHILDREN has become > deprecated as the new syntax for process management is something like.. and @ jerome > make pm.start\_servers greater than pm.min\_spare\_servers and lower than > pm.max\_spare\_servers I am not using FPM as of now. But I will keep configuration given by you guys with me and will definitely use it while moving to FPM. @Piotr > php is compiled _only_ with what I need, nothing more. That explains why your PHP is running with 50% less memory as compared to mine php process. I will also try removing unwanted php extensions. -Rahul ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 5:24pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/17 "2010-06-17T17:24:02Z")
> the FCGI\_OVERLOADED (according to fcgi spec) feature.. to let the webserver > know sooner that there aren’t enough resources on the backend to process the > request rather than after timeouts My purpose of starting this thread is the same as FCGI\_OVERLOADED. I want to tweak my server before it gets overloaded. Thanks to nginx, I haven’t faced any downtime in months. 🙂 (Apart from one in a while timeout alerts I get form uptime monitoring sites) ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 6:27pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/18 "2010-06-17T18:27:53Z")
2010/6/15 Reinis R. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > > > worker\_connections > > > And you can have thousands of open connections because of effective event > > > periodically restarting the childs (done by the master php process)) - it > > > threads (there is a bit difference if you make a lot of backend > > > pm.max\_spare\_servers = 20 > > > pm.max\_requests = 1000 make pm.start\_servers greater than pm.min\_spare\_servers and lower than pm.max\_spare\_servers because at startup, if no connection arrives and if start\_servers is lower than min\_spare\_servers fpm will kill one process per second until current process count reaches min\_spare\_servers. > p.s. afaik the only thing which the php-dev team havent still implemented is > the FCGI\_OVERLOADED (according to fcgi spec) feature.. to let the webserver > know sooner that there aren’t enough resources on the backend to process the > request rather than after timeouts. interesting. Does nginx handle this fcgi response ? You can open a bug on [bugs.php.net](http://bugs.php.net) to request this feature and, if you have so, propose a corresponding patch. ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 6:28pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/19 "2010-06-17T18:28:28Z")
2010/6/15 Rahul B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > By the way I have memcached + APC + CDN + wp-super-cache and now exploring > fastcgi\_cahce by nginx. no i mean memory used by the kernel to cache local files in order not to access file on hardrive. see output of free, the column “cached” ---
**Author:** ![rahul286](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/d78d45/32.png) [@rahul286](https://www.ruby-forum.com/u/rahul286)\ **Post date:** [June 17, 2010, 5:24pm UTC](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218/20 "2010-06-17T17:24:02Z")
Hi jerome All your points duly noted. 🙂 Revising all again… \*worker\_connections = 2048 \*I have its value 1024 (nginx default I guess) I have one very important question here. When we say server load - we mean number of HTTP requests. right? Number of unique pageviews and other sweet number shown by Google Analytic wont be helpful, atleast directly. Is setting up this number very high - like 20480 can adversely affect a high traffic server? > worker\_process = num of CPU. nothing more > I will make this a law for myself. 🙂 > you can save more of OS as there is file caching which is useful > By file caching do u mean php cache which stores page output in html > files > and then serve them via nginx rewrites. > Like wp-super-cache in wordpress world. > By the way I have memcached + APC + CDN + wp-super-cache and now > exploring > fastcgi\_cahce by nginx. I am just obsessed with performance. And I am really not doing this to save my hosting bill. I just want to sustain on single node as long as possible, though some day, our growth forces us to explore path of load-balancing, proxy servers! > a dynamic content nginx is serving from cache won’t generate any load > on the fcgi side as it won’t go there > This sounds nice. > Surprisingly I haven’t seen more about it? -Rahul [Next page](https://www.ruby-forum.com/t/optimizing-worker-processes-worker-connections-php-fcgi-children-any-good-tutorial/190218.md?page=2)