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nginx slow for no reason

August 08, 2011 08:57AM
Hello,
I am running nginx 0.7.67-3 on debian, now without php, mostly serving one empty html. It was working fine for several weeks, handling about 800 connections per second with 2 work processes. Few days ago it started to be very slow, during peak hours almost impossible to connect, but I don't see any bottleneck. I tried increasing the number of workers, using one 1 worker, using multi_accept - nothing helped. What I see on server is that I have more than 500 sockets in SYN_RECV state and nginx process seems to be doing nothing... strace shows this:

gettimeofday({1312807826, 920091}, NULL) = 0
epoll_wait(16, {}, 512, 500) = 0
gettimeofday({1312807827, 421795}, NULL) = 0
epoll_wait(16, {}, 512, 500) = 0
gettimeofday({1312807827, 923222}, NULL) = 0
epoll_wait(16, {}, 512, 500) = 0
gettimeofday({1312807828, 424994}, NULL) = 0
epoll_wait(16, {}, 512, 500) = 0
gettimeofday({1312807828, 926449}, NULL) = 0
epoll_wait(16, {}, 512, 500) = 0
gettimeofday({1312807829, 428064}, NULL) = 0
epoll_wait(16, {}, 512, 500) = 0

like if it had nothing to do - despite those waiting connections... I din't change anything on the server or nginx itself. Maybe the traffic is different (coming from different countries for example), but that shouldn't have any influence.
The traffic is being moved from this old server and domain to a new one. The bad thing is that today the slowness started also on the new server! There we have nginx 1.0.5 from debian dotdeb with php5-fpm. Traffic is to one php script which does one INSERT to the mysql (ad tracking). The new server has 6 GB RAM, 6-core Xeon CPU and is almost idle.

epoll_wait(6, {}, 512, 500) = 0
epoll_wait(6, {}, 512, 500) = 0
epoll_wait(6, {}, 512, 500) = 0
epoll_wait(6, {}, 512, 500) = 0
epoll_wait(6, {}, 512, 500) = 0

What could be the problem?
Subject Author Posted

nginx slow for no reason

Marki555 August 08, 2011 08:57AM

Re: nginx slow for no reason

Antoine Bonavita August 08, 2011 09:28AM

Re: nginx slow for no reason

Marki555 August 08, 2011 09:41AM

Re: nginx slow for no reason

Marki555 August 08, 2011 02:01PM

Re: nginx slow for no reason

Marki555 August 10, 2011 11:02AM

Re: nginx slow for no reason

Antoine Bonavita August 08, 2011 10:10AM

Re: nginx slow for no reason

Maxim Dounin August 08, 2011 10:34AM

Re: nginx slow for no reason

Maxim Dounin August 08, 2011 04:02PM

Re: nginx slow for no reason

Mark Alan August 08, 2011 04:06PM



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