# Nginx worker process hang,cpu load 100% **URL:** \ **Category:** NGINX\ **Created:** [November 13, 2011, 1:06pm UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826 "2011-11-13T13:06:36Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![luislavena](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/0ea827/32.png) [@luislavena](https://www.ruby-forum.com/u/luislavena)\ **Post date:** [November 13, 2011, 1:06pm UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/1 "2011-11-13T13:06:36Z")
Hi, I have faced a trouble with nginx runs as a http revers proxy server,the worker process sometimes hanging there, cpu usage up to 100%,it’s never recovey until i kill the process,below is the detail informations: system environment: [root@host-22 ~]# lsb\_release -a LSB Version: :core-3.1-amd64:core-3.1-ia32:core-3.1-noarch:graphics-3.1-amd64:graphics-3.1-ia32:graphics-3.1-noarch Distributor ID: CentOS Description: CentOS release 5.5 (Final) Release: 5.5 Codename: Final [root@host-22 ~]# [root@host-22 ~]# uname -a Linux host-22 2.6.18-194.el5 #1 SMP Fri Apr 2 14:58:14 EDT 2010 x86\_64 x86\_64 x86\_64 GNU/Linux nginx version: [root@host-22 ~]# /usr/local/nginx/sbin/nginx -V nginx: nginx version: nginx/1.0.4 nginx: built by gcc 4.1.2 20080704 (Red Hat 4.1.2-46) nginx: TLS SNI support disabled nginx: configure arguments: --user=www --group=www –prefix=/usr/local/nginx --with-http\_stub\_status\_module –with-http\_ssl\_module --with-openssl-opt=enable-tlsext –with-http\_sub\_module --with-cc-opt=-O2 --with-cpu-opt=opteron [root@host-22 ~]# (also tested under 1.0.6 and 1.0.9,have the same problem) nginx config( nginx runs as a http revers proxy server): worker\_processes 8; events { use epoll; worker\_connections 5120; } http { sendfile on; keepalive\_timeout 15; … upstream 2012\_servers { server 10.0.7.5:80 max\_fails=2 fail\_timeout=30s; server 10.0.7.6:80 max\_fails=2 fail\_timeout=30s; server 10.0.7.7:80 max\_fails=2 fail\_timeout=30s; server 10.0.7.8:80 max\_fails=2 fail\_timeout=30s; } ``` server { listen 80; server_name test.2012.com ; ... location / { include proxy.conf; proxy_pass http://2012_servers; } ``` … } trouble: [root@host-22 ~]# ps aux|grep -e CPU -e nginx USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 936 0.0 0.0 49328 7572 ? Ss Nov11 2:37 nginx: master process /usr/local/nginx/sbin/nginx www 1130 99.9 0.0 55764 13472 ? R Nov11 2664:28 nginx: worker process www 1216 99.9 0.0 53668 11092 ? R Nov11 2660:23 nginx: worker process www 31057 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process www 31058 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process www 31059 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process www 31060 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process www 31061 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process www 31062 0.8 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process www 31063 0.1 0.0 50816 9012 ? S 19:40 0:00 nginx: worker process www 31064 0.2 0.0 50816 8820 ? S 19:40 0:00 nginx: worker process two nginx worker processes(pid 1130,1216) are hanging. there is nothing significant message i can found in error.log or strace (-p 1130|1216). Grateful for any advice. thanks. Posted at Nginx Forum: > **[nginx worker process hang,cpu load 100%](https://forum.nginx.org/read.php?2,218259,218259#msg-218259)** > > Hi, I have faced a trouble with nginx runs as a http revers proxy server,the worker process sometimes hanging there, cpu usage up to 100%,it's never recovey until i kill the process,below is the detail informations: system environment: \[root@host-22... ---
**Author:** ![Long\_Wan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/13edae/32.png) [@Long\_Wan](https://www.ruby-forum.com/u/Long_Wan)\ **Post date:** [November 13, 2011, 1:36pm UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/2 "2011-11-13T13:36:17Z")
Hello! On Sun, Nov 13, 2011 at 07:06:02AM -0500, Long Wan wrote: > I have faced a trouble with nginx runs as a http revers proxy server,the > worker process sometimes hanging there, cpu usage up to 100%,it’s never > recovey until i kill the process,below is the detail informations: […] > www 31057 0.0 0.0 50816 8820 ? S 19:40 0:00 nginx: > worker process […] > two nginx worker processes(pid 1130,1216) are hanging. there is nothing > significant message i can found in error.log or strace (-p 1130|1216). Please try attaching to a runaway process with gdb and check where it loops, i.e. gdb /path/to/nginx bt n … (repeat ‘n’ several times to see loop) Maxim D. ---
**Author:** ![Long\_Wan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/13edae/32.png) [@Long\_Wan](https://www.ruby-forum.com/u/Long_Wan)\ **Post date:** [November 14, 2011, 2:29am UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/3 "2011-11-14T02:29:05Z")
Hello Maxim,Thanks for your reply, I tried gdb as you tolde me , it reported something : [root@host-22 ~]# gdb /usr/local/nginx/sbin/nginx 1130 GNU gdb (GDB) Red Hat Enterprise Linux (7.0.1-23.el5) Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later [http://gnu.org/licenses/gpl.html](http://gnu.org/licenses/gpl.html) This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type “show copying” and “show warranty” for details. This GDB was configured as “x86\_64-redhat-linux-gnu”. For bug reporting instructions, please see: [http://www.gnu.org/software/gdb/bugs/](http://www.gnu.org/software/gdb/bugs/)… Reading symbols from /usr/local/nginx/sbin/nginx…done. Attaching to program: /usr/local/nginx/sbin/nginx, process 1130 Reading symbols from /lib64/libpthread.so.0…(no debugging symbols found)…done. [Thread debugging using libthread\_db enabled] Loaded symbols for /lib64/libpthread.so.0 Reading symbols from /lib64/libcrypt.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libcrypt.so.1 Reading symbols from /lib64/libpcre.so.0…(no debugging symbols found)…done. Loaded symbols for /lib64/libpcre.so.0 Reading symbols from /lib64/libssl.so.6…(no debugging symbols found)…done. Loaded symbols for /lib64/libssl.so.6 Reading symbols from /lib64/libcrypto.so.6…(no debugging symbols found)…done. Loaded symbols for /lib64/libcrypto.so.6 Reading symbols from /lib64/libdl.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libdl.so.2 Reading symbols from /usr/lib64/libz.so.1…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libz.so.1 Reading symbols from /lib64/libc.so.6…(no debugging symbols found)…done. Loaded symbols for /lib64/libc.so.6 Reading symbols from /lib64/ld-linux-x86-64.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/ld-linux-x86-64.so.2 Reading symbols from /usr/lib64/libgssapi\_krb5.so.2…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libgssapi\_krb5.so.2 Reading symbols from /usr/lib64/libkrb5.so.3…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libkrb5.so.3 Reading symbols from /lib64/libcom\_err.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libcom\_err.so.2 Reading symbols from /usr/lib64/libk5crypto.so.3…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libk5crypto.so.3 Reading symbols from /usr/lib64/libkrb5support.so.0…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libkrb5support.so.0 Reading symbols from /lib64/libkeyutils.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libkeyutils.so.1 Reading symbols from /lib64/libresolv.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libresolv.so.2 Reading symbols from /lib64/libselinux.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libselinux.so.1 Reading symbols from /lib64/libsepol.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libsepol.so.1 Reading symbols from /lib64/libnss\_files.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libnss\_files.so.2 ngx\_http\_upstream\_get\_round\_robin\_peer (pc=0x78166f0, data=) at src/http/ngx\_http\_upstream\_round\_robin.c:413 413 src/http/ngx\_http\_upstream\_round\_robin.c: No such file or directory. in src/http/ngx\_http\_upstream\_round\_robin.c (gdb) bt #0 ngx\_http\_upstream\_get\_round\_robin\_peer (pc=0x78166f0, data=) at src/http/ngx\_http\_upstream\_round\_robin.c:413 #1 0x000000000041a8fc in ngx\_event\_connect\_peer (pc=0x78166f0) at src/event/ngx\_event\_connect.c:24 #2 0x000000000043d1e8 in ngx\_http\_upstream\_connect (r=0x7cf6310, u=0x78166e0) at src/http/ngx\_http\_upstream.c:1089 #3 0x000000000043ea3a in ngx\_http\_upstream\_init\_request (r=0x7cf6310) at src/http/ngx\_http\_upstream.c:628 #4 0x0000000000435185 in ngx\_http\_read\_client\_request\_body (r=0x7cf6310, post\_handler=0x43eec0 \) at src/http/ngx\_http\_request\_body.c:153 #5 0x0000000000456b46 in ngx\_http\_proxy\_handler (r=0x7cf6310) at src/http/modules/ngx\_http\_proxy\_module.c:617 #6 0x000000000042b15c in ngx\_http\_core\_content\_phase (r=0x7cf6310, ph=0x7b5a4e0) at src/http/ngx\_http\_core\_module.c:1339 #7 0x0000000000426817 in ngx\_http\_core\_run\_phases (r=0x7cf6310) at src/http/ngx\_http\_core\_module.c:837 #8 0x000000000042f6d6 in ngx\_http\_process\_request (r=0x7cf6310) at src/http/ngx\_http\_request.c:1650 #9 0x0000000000430314 in ngx\_http\_process\_request\_line (rev=0x7c65578) at src/http/ngx\_http\_request.c:893 #10 0x0000000000420a04 in ngx\_epoll\_process\_events (cycle=, timer=, flags=) at src/event/modules/ngx\_epoll\_module.c:635 #11 0x0000000000419bad in ngx\_process\_events\_and\_timers (cycle=0x784e770) at src/event/ngx\_event.c:245 #12 0x000000000041f528 in ngx\_worker\_process\_cycle (cycle=0x784e770, data=) at src/os/unix/ngx\_process\_cycle.c:800 #13 0x000000000041dc89 in ngx\_spawn\_process (cycle=0x784e770, proc=0x41f470 \, data=0x0, name=0x4652e1 “worker process”, respawn=-4) at src/os/unix/ngx\_process.c:196 #14 0x000000000041eb0b in ngx\_start\_worker\_processes (cycle=0x784e770, n=8, type=-4) at src/os/unix/ngx\_process\_cycle.c:360 #15 0x000000000041fea8 in ngx\_master\_process\_cycle (cycle=0x784e770) at src/os/unix/ngx\_process\_cycle.c:249 #16 0x0000000000406069 in main (argc=1, argv=) at src/core/nginx.c:405 (gdb) n there is no output when type ‘n’, should i recompile nginx with ‘–with-debug’ configure option ? Posted at Nginx Forum: > **[Re: nginx worker process hang,cpu load 100%](https://forum.nginx.org/read.php?2,218259,218280#msg-218280)** > > Hi, I have faced a trouble with nginx runs as a http revers proxy server,the worker process sometimes hanging there, cpu usage up to 100%,it's never recovey until i kill the process,below is the detail informations: system environment: \[root@host-22... ---
**Author:** ![Long\_Wan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/13edae/32.png) [@Long\_Wan](https://www.ruby-forum.com/u/Long_Wan)\ **Post date:** [November 14, 2011, 11:20am UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/4 "2011-11-14T11:20:07Z")
Hello! On Sun, Nov 13, 2011 at 08:28:49PM -0500, Long Wan wrote: > Hello Maxim,Thanks for your reply, I tried gdb as you tolde me , it > reported something : […] > (gdb) bt > #0 ngx\_http\_upstream\_get\_round\_robin\_peer (pc=0x78166f0, data=) at src/http/ngx\_http\_upstream\_round\_robin.c:413 > #1 0x000000000041a8fc in ngx\_event\_connect\_peer (pc=0x78166f0) at > src/event/ngx\_event\_connect.c:24 > #2 0x000000000043d1e8 in ngx\_http\_upstream\_connect (r=0x7cf6310, > u=0x78166e0) at src/http/ngx\_http\_upstream.c:1089 > […] > (gdb) n > > there is no output when type ‘n’, should i recompile nginx with > ‘–with-debug’ configure option ? This looks very similar to this problem, fixed in 1.1.1/1.0.7: ``` *) Bugfix: nginx hogged CPU if all servers in an upstream were ``` marked as “down”. Are you sure you see the same problem in 1.0.9? Maxim D. ---
**Author:** ![Long\_Wan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/13edae/32.png) [@Long\_Wan](https://www.ruby-forum.com/u/Long_Wan)\ **Post date:** [November 14, 2011, 4:59pm UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/5 "2011-11-14T16:59:18Z")
Hello! On Mon, Nov 14, 2011 at 09:37:29AM -0500, Long Wan wrote: […] > I found i made a mistake in nginx.conf, i include a virtual host > configuation like this: > upstream test\_servers { > #Server 10.0.7.4:80 ; > server 10.0.7.5:80 backup; > #Server 10.0.7.6:80 ; > #Server 10.0.7.7:80 ; > } […] > there was only one server in upstream,which marked ‘backup’. after some > test,i found this is the reason. Yes, thank you for report. This is somewhat known issue, ‘backup’ handling needs attention. Maxim D. ---
**Author:** ![Long\_Wan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/13edae/32.png) [@Long\_Wan](https://www.ruby-forum.com/u/Long_Wan)\ **Post date:** [November 15, 2011, 2:57am UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/6 "2011-11-15T02:57:05Z")
Do you plan to fix this issue in next release? Posted at Nginx Forum: > **[Re: nginx worker process hang,cpu load 100%](https://forum.nginx.org/read.php?2,218259,218342#msg-218342)** > > Hi, I have faced a trouble with nginx runs as a http revers proxy server,the worker process sometimes hanging there, cpu usage up to 100%,it's never recovey until i kill the process,below is the detail informations: system environment: \[root@host-22... ---
**Author:** ![Long\_Wan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/13edae/32.png) [@Long\_Wan](https://www.ruby-forum.com/u/Long_Wan)\ **Post date:** [November 14, 2011, 3:38pm UTC](https://www.ruby-forum.com/t/nginx-worker-process-hang-cpu-load-100/213826/7 "2011-11-14T15:38:07Z")
Hello,Maxim. Thanks for you help. I reproduce the problem in nginx-1.0.9, [root@host-22 ~]# /usr/local/nginx/sbin/nginx -V nginx: nginx version: nginx/1.0.9 nginx: built by gcc 4.1.2 20080704 (Red Hat 4.1.2-51) nginx: TLS SNI support disabled nginx: configure arguments: --user=www --group=www –prefix=/usr/local/nginx --with-http\_stub\_status\_module –with-http\_ssl\_module --with-openssl-opt=enable-tlsext –with-http\_sub\_module --with-cc-opt=-O2 --with-cpu-opt=opteron –add-module=…/ngx\_cache\_purge-1.4 [root@host-22 ~]# [root@host-22 ~]# [root@host-22 ~]# ps aux|grep -e CPU -e nginx USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 569 0.0 0.0 49016 6884 ? Ss 21:59 0:00 nginx: master process /usr/local/nginx/sbin/nginx www 587 97.3 0.0 49380 7556 ? R 22:00 10:16 nginx: worker process www 588 93.8 0.0 49380 7556 ? R 22:00 9:54 nginx: worker process www 614 43.1 0.0 49412 7584 ? T 22:01 4:07 nginx: worker process root 781 0.0 0.1 95984 19684 pts/0 S+ 22:06 0:00 gdb /usr/local/nginx/sbin/nginx 614 www 876 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process www 877 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process www 878 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process www 879 0.0 0.0 50504 8660 ? S 22:10 0:00 nginx: worker process www 880 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process www 881 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process www 882 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process www 883 0.0 0.0 50504 8464 ? S 22:10 0:00 nginx: worker process root 954 0.0 0.0 61168 788 pts/1 S+ 22:10 0:00 grep -e CPU -e nginx [root@host-22 ~]# [root@host-22 ~]# gdb /usr/local/nginx/sbin/nginx 614 GNU gdb (GDB) Red Hat Enterprise Linux (7.0.1-23.el5) Copyright (C) 2009 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later [http://gnu.org/licenses/gpl.html](http://gnu.org/licenses/gpl.html) This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type “show copying” and “show warranty” for details. This GDB was configured as “x86\_64-redhat-linux-gnu”. For bug reporting instructions, please see: [http://www.gnu.org/software/gdb/bugs/](http://www.gnu.org/software/gdb/bugs/)… Reading symbols from /usr/local/nginx/sbin/nginx…done. Attaching to program: /usr/local/nginx/sbin/nginx, process 614 Reading symbols from /lib64/libpthread.so.0…(no debugging symbols found)…done. [Thread debugging using libthread\_db enabled] Loaded symbols for /lib64/libpthread.so.0 Reading symbols from /lib64/libcrypt.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libcrypt.so.1 Reading symbols from /lib64/libpcre.so.0…(no debugging symbols found)…done. Loaded symbols for /lib64/libpcre.so.0 Reading symbols from /lib64/libssl.so.6…(no debugging symbols found)…done. Loaded symbols for /lib64/libssl.so.6 Reading symbols from /lib64/libcrypto.so.6…(no debugging symbols found)…done. Loaded symbols for /lib64/libcrypto.so.6 Reading symbols from /lib64/libdl.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libdl.so.2 Reading symbols from /usr/lib64/libz.so.1…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libz.so.1 Reading symbols from /lib64/libc.so.6…(no debugging symbols found)…done. Loaded symbols for /lib64/libc.so.6 Reading symbols from /lib64/ld-linux-x86-64.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/ld-linux-x86-64.so.2 Reading symbols from /usr/lib64/libgssapi\_krb5.so.2…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libgssapi\_krb5.so.2 Reading symbols from /usr/lib64/libkrb5.so.3…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libkrb5.so.3 Reading symbols from /lib64/libcom\_err.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libcom\_err.so.2 Reading symbols from /usr/lib64/libk5crypto.so.3…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libk5crypto.so.3 Reading symbols from /usr/lib64/libkrb5support.so.0…(no debugging symbols found)…done. Loaded symbols for /usr/lib64/libkrb5support.so.0 Reading symbols from /lib64/libkeyutils.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libkeyutils.so.1 Reading symbols from /lib64/libresolv.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libresolv.so.2 Reading symbols from /lib64/libselinux.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libselinux.so.1 Reading symbols from /lib64/libsepol.so.1…(no debugging symbols found)…done. Loaded symbols for /lib64/libsepol.so.1 Reading symbols from /lib64/libnss\_files.so.2…(no debugging symbols found)…done. Loaded symbols for /lib64/libnss\_files.so.2 ngx\_http\_upstream\_get\_peer (pc=0x54ae260, data=) at src/http/ngx\_http\_upstream\_round\_robin.c:632 632 if (reset++) { (gdb) bt #0 ngx\_http\_upstream\_get\_peer (pc=0x54ae260, data=) at src/http/ngx\_http\_upstream\_round\_robin.c:632 #1 ngx\_http\_upstream\_get\_round\_robin\_peer (pc=0x54ae260, data=) at src/http/ngx\_http\_upstream\_round\_robin.c:425 #2 0x000000000041a99c in ngx\_event\_connect\_peer (pc=0x54ae960) at src/event/ngx\_event\_connect.c:24 #3 0x000000000043d5a8 in ngx\_http\_upstream\_connect (r=0x54c3b30, u=0x54ae250) at src/http/ngx\_http\_upstream.c:1103 #4 0x000000000043ee0a in ngx\_http\_upstream\_init\_request (r=0x54c3b30) at src/http/ngx\_http\_upstream.c:631 #5 0x00000000004354a5 in ngx\_http\_read\_client\_request\_body (r=0x54c3b30, post\_handler=0x43f310 \) at src/http/ngx\_http\_request\_body.c:154 #6 0x00000000004572d6 in ngx\_http\_proxy\_handler (r=0x54c3b30) at src/http/modules/ngx\_http\_proxy\_module.c:617 #7 0x000000000042b47c in ngx\_http\_core\_content\_phase (r=0x54c3b30, ph=0x583ffd8) at src/http/ngx\_http\_core\_module.c:1365 #8 0x0000000000426967 in ngx\_http\_core\_run\_phases (r=0x54c3b30) at src/http/ngx\_http\_core\_module.c:861 #9 0x000000000042fa66 in ngx\_http\_process\_request (r=0x54c3b30) at src/http/ngx\_http\_request.c:1665 #10 0x00000000004306a4 in ngx\_http\_process\_request\_line (rev=0x5843fc0) at src/http/ngx\_http\_request.c:911 #11 0x0000000000419e86 in ngx\_event\_process\_posted (cycle=, posted=0x68bd88) at src/event/ngx\_event\_posted.c:39 #12 0x000000000041f608 in ngx\_worker\_process\_cycle (cycle=0x560f670, data=) at src/os/unix/ngx\_process\_cycle.c:801 #13 0x000000000041dd69 in ngx\_spawn\_process (cycle=0x560f670, proc=0x41f550 \, data=0x0, name=0x466581 “worker process”, respawn=-4) at src/os/unix/ngx\_process.c:196 #14 0x000000000041ebeb in ngx\_start\_worker\_processes (cycle=0x560f670, n=8, type=-4) at src/os/unix/ngx\_process\_cycle.c:360 #15 0x000000000041ff88 in ngx\_master\_process\_cycle (cycle=0x560f670) at src/os/unix/ngx\_process\_cycle.c:249 #16 0x00000000004060d9 in main (argc=1, argv=) at src/core/nginx.c:405 (gdb) n 425 rrp-\>current = ngx\_http\_upstream\_get\_peer(rrp-\>peers); (gdb) n 435 if (!(rrp-\>tried[n] & m)) { (gdb) n 460 if (pc-\>tries == 0) { (gdb) n 464 if (–i == 0) { (gdb) n 425 rrp-\>current = ngx\_http\_upstream\_get\_peer(rrp-\>peers); (gdb) n 435 if (!(rrp-\>tried[n] & m)) { (gdb) n 460 if (pc-\>tries == 0) { (gdb) n 464 if (–i == 0) { (gdb) n 425 rrp-\>current = ngx\_http\_upstream\_get\_peer(rrp-\>peers); (gdb) n 435 if (!(rrp-\>tried[n] & m)) { (gdb) n 460 if (pc-\>tries == 0) { (gdb) n 464 if (–i == 0) { (gdb) I found i made a mistake in nginx.conf, i include a virtual host configuation like this: upstream test\_servers { #Server 10.0.7.4:80 ; server 10.0.7.5:80 backup; #Server 10.0.7.6:80 ; #Server 10.0.7.7:80 ; } ``` server { listen 80; server_name test.org ; access_log /data1/logs/$host.access.log main; location / { include proxy.conf; proxy_pass http://test_servers; } } ``` there was only one server in upstream,which marked ‘backup’. after some test,i found this is the reason. but when i test the nginx.conf syntax by using nginx -t,the result is ok. [root@host-22 ~]# /usr/local/nginx/sbin/nginx -t nginx: the configuration file /usr/local/nginx/conf/nginx.conf syntax is ok nginx: configuration file /usr/local/nginx/conf/nginx.conf test is successful [root@host-22 ~]# i think nginx should warn me when that situation,haha… Posted at Nginx Forum: > **[Re: nginx worker process hang,cpu load 100%](https://forum.nginx.org/read.php?2,218259,218315#msg-218315)** > > Hi, I have faced a trouble with nginx runs as a http revers proxy server,the worker process sometimes hanging there, cpu usage up to 100%,it's never recovey until i kill the process,below is the detail informations: system environment: \[root@host-22...