# Nginx high active connections

**URL:** <https://www.ruby-forum.com/t/nginx-high-active-connections/221172>\
**Category:** NGINX\
**Created:** [July 3, 2012, 2:46pm UTC](https://www.ruby-forum.com/t/nginx-high-active-connections/221172 "2012-07-03T14:46:20Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\
**Post date:** [July 3, 2012, 2:46pm UTC](https://www.ruby-forum.com/t/nginx-high-active-connections/221172/1 "2012-07-03T14:46:20Z")

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We have couple of servers. nginx takes the web requests

Active connections in the range of 400-450 is okay

but sometimes it goes to like 4,000. at this point in time. This is  
abnormal

What does this mean? Is it that nginx is not able to take the load?

Or is it that the DB Server behind nginx is taking time? Or is it that  
the Ubuntu server is not network optimized? Or is it that the RAM is  
low?

Tahseen

Posted at Nginx Forum:

> **[nginx high active connections](https://forum.nginx.org/read.php?2,228238,228238#msg-228238)**
>
> We have couple of servers. nginx takes the web requests Active connections in the range of 400-450 is okay but sometimes it goes to like 4,000. at this point in time. This is abnormal What does this mean? Is it that nginx is not able to take the l

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**Author:** ![tahseen](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/8edcca/32.png) [@tahseen](https://www.ruby-forum.com/u/tahseen)\
**Post date:** [July 3, 2012, 5:10pm UTC](https://www.ruby-forum.com/t/nginx-high-active-connections/221172/2 "2012-07-03T17:10:42Z")

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> Active connections in the range of 400-450 is okay  
> but sometimes it goes to like 4,000. at this point in time. This is abnormal

> What does this mean? Is it that nginx is not able to take the load?

It is rarely the webserver itself which can’t handle the  
load/connections (having even 10k connections is no big deal) but it is  
hard to get to any conclusions and/or give any solutions knowing only 2  
numbers - 400 / 4000. One needs at least some application  
specifics (is there a dynamic language involved (php/python/…) or only  
static files are being served / are there any db backends  
involved / does the undelaying filesystem can handle the load (no wa?)  
etc etc?).

Just out of experience 2 cases come into mind - it’s either slowdown of  
the application - single request starts to take up too much  
server time and then the rest just pile up.  
Other possibility is some sort of DDOS (but I would put this as less  
likely case).

First thing to do is to check the logs:

- check the nginx error log if there are notification (of file  
descriptors running out of workers being too few / upstream servers  
not responding)

- if you use php (with fpm) check the error\_log too - lines like ‘[pool  
www] seems busy (you may need to increase pm.start\_servers,  
or pm.min/max\_spare\_servers)’ might indicate that there are sudden  
changes in request patterns or execution speed and all worker  
childs are busy. It’s also useful to enable set request\_slowlog\_timeout  
so php logs any request taking too much time to execute.

- if you use any DBs check those logs too (like MySQL .err log or best  
if you have a slow query log enabled ( log\_slow\_queries /  
long\_query\_time = 2 ))

There is no magical quick fix or answer to your question 🙂

rr

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<div class="post-metadata">

**Author:** ![tahseen](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/t/8edcca/32.png) [@tahseen](https://www.ruby-forum.com/u/tahseen)\
**Post date:** [July 14, 2012, 6:05pm UTC](https://www.ruby-forum.com/t/nginx-high-active-connections/221172/3 "2012-07-14T18:05:43Z")

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So situation is this. nginx takes the incoming request and then passes  
it on to Tomcat, which is running a servlet. The servlet responses back  
to nginx and at the same time does logging of various request  
information via JMS

Now nginx definitely is capable of handling high requests.

I increased Tomcat threadpool value from 500 to 2,000 and made heapsize  
4GB

JMSMaxConnections was set to 10 and JMSMaxActiveConnections was set to  
5

I made them 100 and 50 respectively. After that it drastically reduced  
nginx active connections

But my questions is have I done justice to JMS connection values? Aren’t  
they suppose to be more? LIke 500 or so

Posted at Nginx Forum:

> **[Re: nginx high active connections](https://forum.nginx.org/read.php?2,228238,228589#msg-228589)**
>
> We have couple of servers. nginx takes the web requests Active connections in the range of 400-450 is okay but sometimes it goes to like 4,000. at this point in time. This is abnormal What does this mean? Is it that nginx is not able to take the l