# CPU load monitoring / dynamically limit number of connections to server **URL:** \ **Category:** NGINX\ **Created:** [May 19, 2016, 5:12pm UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651 "2016-05-19T17:12:19Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\ **Post date:** [May 19, 2016, 5:12pm UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651/1 "2016-05-19T17:12:19Z")
Hi to all, Is there a way to monitor the busyness of my dedicated server cpu cores and stop serving new connections passed a given cpu load threshold? Put another way, what is the standard approach/technique to dynamically limit the maximum number of connections my machine can cope with? Thank you, ohenley Posted at Nginx Forum: > **[CPU load monitoring / dynamically limit number of connections to server](https://forum.nginx.org/read.php?2,267003,267003#msg-267003)** > > Hi to all, Is there a way to monitor the busyness of my dedicated server cpu cores and stop serving new connections passed a given cpu load threshold? Put another way, what is the standard approach/technique to dynamically limit the maximum number of... ---
**Author:** ![ohenley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/6de8d8/32.png) [@ohenley](https://www.ruby-forum.com/u/ohenley)\ **Post date:** [May 20, 2016, 8:26pm UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651/2 "2016-05-20T20:26:47Z")
[Module ngx\_http\_limit\_conn\_module](http://nginx.org/en/docs/http/ngx_http_limit_conn_module.html) - not system load based though – Anoop P Alias ---
**Author:** ![ohenley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/6de8d8/32.png) [@ohenley](https://www.ruby-forum.com/u/ohenley)\ **Post date:** [May 20, 2016, 9:46pm UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651/3 "2016-05-20T21:46:49Z")
‎Bear in mind one IP can be many eyeballs. I use the module with a setting of 10 per IP. I set the firewall to a higher limit to allow some non-web services, but not infinite. This can fight back a very unsophisticated DOS attack. A real DOS is distributed, so the IP limit won’t be useful. I had a document hit Twitter and their servers hammered my lowly VPS. Besides an IP limit, I suggest a rewrite to eliminate hot linking, which effectively is what Twitter can do. If they tweet a link to a webpage, no problem. That would limit those twitter users to each individually set their browser ‎to a webpage, which slows the requests. Out of paranoia, I blocked all of Twitter IP space. The same for Facebook. Again, the eyeballs can use their ISP via a link. I’m not comfortable with social media companies directly accessing my server since they have huge data bandwidth. That leaves large corporations and universities as the situation where one IP is really many eyeballs. A connection limit of 10 will be too low in these cases occasionally, but you have to set the limit somewhere. Original Message From: Anoop A. Sent: Friday, May 20, 2016 11:26 AM To: Nginx Reply To: removed\_email\_address@domain.invalid Subject: Re: CPU load monitoring / dynamically limit number of connections to server [Module ngx\_http\_limit\_conn\_module](http://nginx.org/en/docs/http/ngx_http_limit_conn_module.html) - not system load based though – Anoop P Alias * * * nginx mailing list removed\_email\_address@domain.invalid [http://mailman.nginx.org/mailman/listinfo/nginx](http://mailman.nginx.org/mailman/listinfo/nginx) ---
**Author:** ![ohenley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/6de8d8/32.png) [@ohenley](https://www.ruby-forum.com/u/ohenley)\ **Post date:** [May 21, 2016, 9:37pm UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651/4 "2016-05-21T21:37:27Z")
Found it: [https://www.scalyr.com/community/guides/how-to-monitor-nginx-the-essential-guide](https://www.scalyr.com/community/guides/how-to-monitor-nginx-the-essential-guide) Posted at Nginx Forum: > **[Re: CPU load monitoring / dynamically limit number of connections to server](https://forum.nginx.org/read.php?2,267003,267019#msg-267019)** > > Hi to all, Is there a way to monitor the busyness of my dedicated server cpu cores and stop serving new connections passed a given cpu load threshold? Put another way, what is the standard approach/technique to dynamically limit the maximum number of... ---
**Author:** ![ohenley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/6de8d8/32.png) [@ohenley](https://www.ruby-forum.com/u/ohenley)\ **Post date:** [May 25, 2016, 4:07pm UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651/5 "2016-05-25T16:07:30Z")
Thx gariac. Posted at Nginx Forum: > **[Re: CPU load monitoring / dynamically limit number of connections to server](https://forum.nginx.org/read.php?2,267003,267145#msg-267145)** > > Hi to all, Is there a way to monitor the busyness of my dedicated server cpu cores and stop serving new connections passed a given cpu load threshold? Put another way, what is the standard approach/technique to dynamically limit the maximum number of... ---
**Author:** ![ohenley](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/6de8d8/32.png) [@ohenley](https://www.ruby-forum.com/u/ohenley)\ **Post date:** [May 22, 2016, 3:39am UTC](https://www.ruby-forum.com/t/cpu-load-monitoring-dynamically-limit-number-of-connections-to-server/244651/6 "2016-05-22T03:39:37Z")
Does that really limit per the OP’s request? Reading the document, it seems like a monitoring module, but not something that limits nginx. For example, ulimit is just a linux command. Maybe you could set a chron job to sniff the load based on this monitoring and adjust system parameters accordingly. (Beware of positive feedback loops.! This was my method to set limits on nginx. First, download [http://www.labs.hpe.com/research/linux/httperf/](http://www.labs.hpe.com/research/linux/httperf/) I found my server could handle 3000 requests per minute. Note this is running httperf ON the server itself. This does not include the connection to the Internet. But now you know how much abuse the server can take. Then I ran httperf over the Internet from a number of different ISPs. The performace was more like 100 requests per second at best. Clearly the pipe I share is the limiting factor. ‎I pulled a somewhat arbitrary 10 users at a time limit, which is actually real life most of the time. I’m not CNN or a porn site. So I set the limit request to 10 per second. Remember every photo, document, etc. takes one request. This is barely scientific, but it is better than nothing. Original Message From: ohenley Sent: Saturday, May 21, 2016 12:37 PM To: removed\_email\_address@domain.invalid Reply To: removed\_email\_address@domain.invalid Subject: Re: CPU load monitoring / dynamically limit number of connections to server Found it: [https://www.scalyr.com/community/guides/how-to-monitor-nginx-the-essential-guide](https://www.scalyr.com/community/guides/how-to-monitor-nginx-the-essential-guide) Posted at Nginx Forum: > **[Re: CPU load monitoring / dynamically limit number of connections to server](https://forum.nginx.org/read.php?2,267003,267019#msg-267019)** > > Hi to all, Is there a way to monitor the busyness of my dedicated server cpu cores and stop serving new connections passed a given cpu load threshold? Put another way, what is the standard approach/technique to dynamically limit the maximum number of... * * * nginx mailing list removed\_email\_address@domain.invalid [http://mailman.nginx.org/mailman/listinfo/nginx](http://mailman.nginx.org/mailman/listinfo/nginx)