No response nginx

Server NGINX
1

Hi.

I have a problem with nginx-1.1.16 uses proxy_cache_lock on.
When high load or many request to nginx, Suddenly nginx seems hang,
no response at all.
In netstat “SYN_RECV”,“CLOSE_WAIT” too many. This problem needs
restarting nginx, and “CLOSE_WAIT” clear.

There is no problem in front-end nginx servers, but backends one.

Any clue?

–
shin fukuda [email protected]

2

Hello!

On Thu, Apr 05, 2012 at 09:25:44AM +0900, shin fukuda wrote:

Any clue?
I would suggest you are hitting some system limits. Check nginx
and system logs, as well as various system stats. Check the state
of nginx worker processes, most importantly wait channel (wchan,
“ps -alx” should show one at least on FreeBSD and Linux).

Maxim D.

3

Hello, Maxim.

On Thu, 5 Apr 2012 18:56:11 +0400
Maxim D. [email protected] wrote:

restarting nginx, and “CLOSE_WAIT” clear.

There is no problem in front-end nginx servers, but backends one.

Any clue?

I would suggest you are hitting some system limits. Check nginx
and system logs, as well as various system stats. Check the state
of nginx worker processes, most importantly wait channel (wchan,
“ps -alx” should show one at least on FreeBSD and Linux).

Set kernel parameter like

…
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_keepalive_time = 300

But, no good result so far.

Anyway, I check workers details, and find this,

15832 write(4, “2012/04/04 19:56:10 [info] 15832#0: sigtimedwait()
failed (4: Interrupted system”…, 87) = 87
15832 rt_sigtimedwait([ALRM IO RT_12 RT_13], 0x691220) = -1 EAGAIN
(Resource temporarily unavailable)
15832 rt_sigtimedwait([ALRM IO RT_12 RT_13], 0x691220) = -1 EAGAIN
(Resource temporarily unavailable)
…
…

Is this normal status ?

Maxim D.

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–
shin fukuda [email protected]