# No response nginx **URL:** \ **Category:** NGINX\ **Created:** [April 5, 2012, 2:26am UTC](https://www.ruby-forum.com/t/no-response-nginx/218592 "2012-04-05T02:26:17Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![dubstep](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/cdc98d/32.png) [@dubstep](https://www.ruby-forum.com/u/dubstep)\ **Post date:** [April 5, 2012, 2:26am UTC](https://www.ruby-forum.com/t/no-response-nginx/218592/1 "2012-04-05T02:26:17Z")
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 [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![shin\_fukuda](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ecc23a/32.png) [@shin\_fukuda](https://www.ruby-forum.com/u/shin_fukuda)\ **Post date:** [April 5, 2012, 4:56pm UTC](https://www.ruby-forum.com/t/no-response-nginx/218592/2 "2012-04-05T16:56:57Z")
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. ---
**Author:** ![shin\_fukuda](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ecc23a/32.png) [@shin\_fukuda](https://www.ruby-forum.com/u/shin_fukuda)\ **Post date:** [April 6, 2012, 3:47am UTC](https://www.ruby-forum.com/t/no-response-nginx/218592/3 "2012-04-06T03:47:51Z")
Hello, Maxim. On Thu, 5 Apr 2012 18:56:11 +0400 Maxim D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) 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. > > * * * > > nginx mailing list > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [mailman.nginx.org archive](http://mailman.nginx.org/mailman/listinfo/nginx) – shin fukuda [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)