high Traffic setup problem, module status don't deliver data

Aleksandar Lazic al-nginx at none.at
Tue Feb 11 13:14:14 UTC 2014


Am 11-02-2014 13:28, schrieb Maxim Dounin:
> Hello!
> On Tue, Feb 11, 2014 at 01:10:59PM +0100, Aleksandar Lazic wrote:
>> Am 11-02-2014 12:48, schrieb Maxim Dounin:
>> >Hello!
>> >
>> >On Tue, Feb 11, 2014 at 12:34:59PM +0100, Aleksandar Lazic wrote:
>> >
>> [snipp]
>> >>>You haven't shown your server level configuration.
>> >>>Do you use deferred accept?
>> >>
>> >>yes
>> >>
>> >>listen       <IP>:80 deferred default_server;
>> >
>> >Try switching it off, there could be a problem if kernel decides
>> >to switch to syncookies, see this ticket for details:
>> >
>> >http://trac.nginx.org/nginx/ticket/353
>> >
>> >(The problem is fixed in 1.5.10, and 1.4.5 will have the fix,
>> >too.)
>> Ok thanks.
>> I have now removed deferred  and added backlog=1024
> Does it actually solve the problem?  It also would be intresting
> to know what exactly did it - removing deferred or adding backlog?

Due to the fact that we have mostly in the morning our highest traffic I 
can tell you this tomorrow.
I still search for a useable load testing setup.
Currently I have one server (1 GB) with


I will try today


But if anybody have a suggestion for distributed load testing service 
I'm open eared.

What I also have seen is that.

netstat -s|egrep 'listen queue|SYNs to LISTEN sockets dropped'
     131753 times the listen queue of a socket overflowed
     18195732 SYNs to LISTEN sockets dropped

a second later.

netstat -s|egrep 'listen queue|SYNs to LISTEN sockets dropped'
     131753 times the listen queue of a socket overflowed
     18195743 SYNs to LISTEN sockets dropped

What could be this the reason?

> (As for backlog size, I usually set it to something big enough to
> accomodate about 1 or 2 seconds of expected peek connection rate.
> That is, 1024 is good enough for about 500 connections per second.
> But with deferred on Linux, it looks like deferred connection are
> sitting in the same queue as normal ones, and this may drastically
> change things.)

OK. That means with deferred I should double or divide the listening 

>> Should I add deferred again when I update to 1.4.5?
> It should be safe, though I don't recommend it unless it's
> beneficial in your setup.

OK. Thanks for now I will not activate it for the current setup.

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