Today is the third time within the last week that the nginx server crashed down, causing the website to only return "502 Bad Gateway" errors. In the error log, I can find the following line:

2014/04/24 05:11:53 [alert] 32094#0: worker process 32095 exited on signal 11

I have searched for other users having the same error message, but usually it was caused by some custom plugin they installed. I don't use any plugins (by that I mean I use debian's stable repository of the "nginx-full" package. I'm not sure if they deliver some custom plugins by default).

What could be causing the issue for me?



#nginx -v
nginx version: nginx/1.2.1

#nginx -V
nginx version: nginx/1.2.1
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-log-path=/var/log/nginx/access.log --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --lock-path=/var/lock/nginx.lock --pid-path=/var/run/nginx.pid --with-pcre-jit --with-debug --with-http_addition_module --with-http_dav_module --with-http_geoip_module --with-http_gzip_static_module --with-http_image_filter_module --with-http_realip_module --with-http_stub_status_module --with-http_ssl_module --with-http_sub_module --with-http_xslt_module --with-ipv6 --with-sha1=/usr/include/openssl --with-md5=/usr/include/openssl --with-mail --with-mail_ssl_module --add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-auth-pam --add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-echo --add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-upstream-fair --add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-dav-ext-module

#uname -a
Linux [hostname removed] 3.2.0-4-amd64 #1 SMP Debian 3.2.54-2 x86_64 GNU/Linux

nginx.conf
user www-data;
worker_processes 8;
pid /var/run/nginx.pid;

events {
worker_connections 16384;
# multi_accept on;
}

worker_rlimit_nofile 32768;

http {

##
# Basic Settings
##

sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 5;
types_hash_max_size 2048;
server_tokens off;

server_names_hash_bucket_size 64;
server_name_in_redirect off;

include /etc/nginx/mime.types;
default_type application/octet-stream;

##
# Logging Settings
##

access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;

##
# Gzip Settings
##

gzip on;
gzip_buffers 16 8k;
gzip_comp_level 6;
gzip_http_version 1.1;
gzip_min_length 10;
gzip_types text/plain text/css image/png image/gif image/jpeg application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript image/x-icon;
gzip_vary on;
gzip_proxied any;
gzip_disable "MSIE [1-6]\.(?!.*SV1)";

##
# Proxy Settings
##

proxy_send_timeout 90;
proxy_read_timeout 90;
proxy_buffer_size 4k;
proxy_buffers 4 32k;
proxy_busy_buffers_size 64k;
proxy_temp_file_write_size 64k;

include /etc/nginx/conf.d/*.conf; # there is no file in that dir
include /etc/nginx/sites-enabled/*; # only some files with pretty basic server{} blocks
}