NGINX + PHP5-FPM segfaults under high load
I have been dealing with this problem all day and it is driving me insane. All Google results and searches here lead to dead ends. I hope someone can work with me to provide a solution for myself and future victims. Here we go.
I am running a very popular website with over 3M page views a day. On average that is 34 page views per second, but more realistically, during peak hours, it gets to over 300 page views per second. Think of these as requests.
I am running a Ubuntu 10.04 64-bit server with 2 E5620 CPUs, 12GB RAM, and a Micron P300 6Gb/s SSD. During the peak hours the CPU and memory load is average (20-30% CPU and half of memory is used).
The software that powers this site is: NGINX, MySQL, PHP5-FPM, PHP-APC, and Memcached. Ok, now finally the meat of the post, here are my error logs. There a bunch of these errors logged.
/var/log/php5-fpm
Jul 20 14:49:47.289895 [NOTICE] fpm is running, pid 29373
Jul 20 14:49:47.337092 [NOTICE] ready to handle connections
Jul 20 14:51:23.957504 [ERROR] [pool www] unable to retrieve process activity of one or more child(ren). Will try again later.
Jul 20 14:51:41.846439 [WARNING] [pool www] child 29534 exited with code 1 after 114.518174 seconds from start
Jul 20 14:51:41.846797 [NOTICE] [pool www] child 29597 started
Jul 20 14:51:41.896653 [WARNING] [pool www] child 29408 exited on signal 11 SIGSEGV after 114.596706 seconds from start
Jul 20 14:51:41.897178 [NOTICE] [pool www] child 29598 started
Jul 20 14:51:41.903286 [WARNING] [pool www] child 29398 exited with code 1 after 114.605761 seconds from start
Jul 20 14:51:41.903719 [NOTICE] [pool www] child 29600 started
Jul 20 14:51:41.907816 [WARNING] [pool www] child 29437 exited with code 1 after 114.601417 seconds from start
Jul 20 14:51:41.908253 [NOTICE] [pool www] child 29601 started
Jul 20 14:51:41.916002 [WARNING] [pool www] child 29513 exited with code 1 after 114.592514 seconds from start
Jul 20 14:51:41.916501 [NOTICE] [pool www] child 29602 started
Jul 20 14:51:41.916558 [WARNING] [pool www] child 29494 exited on signal 11 SIGSEGV after 114.597355 seconds from start
Jul 20 14:51:41.916873 [NOTICE] [pool www] child 29603 started
Jul 20 14:51:41.921389 [WARNING] [pool www] child 29502 exited with code 1 after 114.600405 seconds from start
/var/log/nginx/error.log 2011/07/20 15:48:42 [error] 29583#0: *569743 readv() failed (104: Connection reset by peer) while reading upstream, client: 77.223.197.193, server: domain.com, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
2011/07/20 15:48:42 [error] 29578#0: *571695 readv() failed (104: Connection reset by peer) while reading upstream, client: 150.70.64.196, server: domain.com, request: "GET /page HTTP/1.0", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
2011/07/20 15:48:42 [error] 29581#0: *571050 readv() failed (104: Connection reset by peer) while reading upstream, client: 110.136.157.66, server: domain.com, request: "GET /page HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
2011/07/20 15:48:42 [error] 29581#0: *564892 readv() failed (104: Connection reset by peer) while reading upstream, client: 110.136.161.214, server: domain.com, request: "GET /page HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
2011/07/20 15:48:42 [error] 29585#0: *456171 readv() failed (104: Connection reset by peer) while reading upstream, client: 93.223.33.135, server: domain.com, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
2011/07/20 15:48:42 [error] 29585#0: *471192 readv() failed (104: Connection reset by peer) while reading upstream, client: 74.90.33.142, server: domain.com, request: "GET /page HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
2011/07/20 15:48:42 [error] 29580#0: *570132 readv() failed (104: Connection reset by peer) while reading upstream, client: 180.246.182.191, server: domain.com, request: "GET /page HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "www.domain.com"
Finally, I want to point out that I did try to disable PHP-APC to see if it was a bug with the opt cacher, but the segfaults still persisted. I also have PHP5-SUHOSIN installed and I disabled it too, but the errors still keep happening.
Answer
This issue just happend to me.
PHP5-FPM was having segfaults on most of its children. In my case, we had 0bytes available on the harddisk. A quick log shredding stopped the segfaults.