我有一个Rails(3.2)应用程序,它运行在云平台上的Nginx和unicorn上. “盒子”在Ubuntu 12.04上运行.

当系统负载大约为70％或更高时,Nginx突然(并且看似随机)开始抛出502 Bad网关错误;当负载较小时,没有什么比这更好的了.我已经尝试了不同数量的核心(4,6,10 – 我可以“改变硬件”,因为它在云平台上),情况总是一样的. (cpu负载类似于系统负载,用户空间为55％,其余为系统和被盗,有足够的可用内存,没有交换.)

502通常分批进行,但并非总是如此.

(我每个核心运行一个独角兽工作者,以及一个或两个Nginx工作者.当在10个核心上运行时,请参阅下面配置的相关部分.)

我真的不知道如何跟踪这些错误的原因.我怀疑它可能与麒麟工人无法服务(及时？)有关但它看起来很奇怪,因为它们似乎没有使cpu饱和,我认为他们没有理由等待IO(但我不喜欢不知道如何确保这一点.

请你帮我看看如何找到原因？

Unicorn config(unicorn.rb)：

worker_processes 10
working_directory "/var/www/app/current"
listen "/var/www/app/current/tmp/sockets/unicorn.sock",:backlog => 64
listen 2007,:tcp_nopush => true
timeout 90
pid "/var/www/app/current/tmp/pids/unicorn.pid"
stderr_path "/var/www/app/shared/log/unicorn.stderr.log"
stdout_path "/var/www/app/shared/log/unicorn.stdout.log"
preload_app true
GC.respond_to?(:copy_on_write_friendly=) and
  GC.copy_on_write_friendly = true
check_client_connection false

before_fork do |server,worker|
  ... I believe the stuff here is irrelevant ...
end
after_fork do |server,worker|
  ... I believe the stuff here is irrelevant ...
end

和ngnix配置：

/etc/Nginx/Nginx.conf：

worker_processes 2;
worker_rlimit_nofile 2048;
user www-data www-admin;
pid /var/run/Nginx.pid;
error_log /var/log/Nginx/Nginx.error.log info;

events {
  worker_connections 2048;
  accept_mutex on; # "on" if Nginx worker_processes > 1
  use epoll;
}

http {
    include       /etc/Nginx/mime.types;
    default_type  application/octet-stream;
    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';
    access_log  /var/log/Nginx/access.log  main;
    # optimialization efforts
    client_max_body_size        2m;
    client_body_buffer_size     128k;
    client_header_buffer_size   4k;
    large_client_header_buffers 10 4k;  # one for each core or one for each unicorn worker?
    client_body_temp_path       /tmp/Nginx/client_body_temp;

    include /etc/Nginx/conf.d/*.conf;
}

/etc/Nginx/conf.d/app.conf：

sendfile on;
tcp_nopush on;
tcp_nodelay off;
gzip on;
gzip_http_version 1.0;
gzip_proxied any;
gzip_min_length 500;
gzip_disable "MSIE [1-6]\.";
gzip_types text/plain text/css text/javascript application/x-javascript;

upstream app_server {
  # fail_timeout=0 means we always retry an upstream even if it Failed
  # to return a good HTTP response (in case the Unicorn master nukes a
  # single worker for timing out).
  server unix:/var/www/app/current/tmp/sockets/unicorn.sock fail_timeout=0;
}

server {
  listen 80 default deferred;
  server_name _;
  client_max_body_size 1G;
  keepalive_timeout 5;
  root /var/www/app/current/public;

  location ~ "^/assets/.*" {
      ...
  }

  # Prefer to serve static files directly from Nginx to avoid unnecessary
  # data copies from the application server.
  try_files $uri/index.html $uri.html $uri @app;

  location @app {
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Host $http_host;
    proxy_redirect off;

    proxy_pass http://app_server;

    proxy_connect_timeout      90;
    proxy_send_timeout         90;
    proxy_read_timeout         90;

    proxy_buffer_size          128k;
    proxy_buffers              10 256k;  # one per core or one per unicorn worker?
    proxy_busy_buffers_size    256k;
    proxy_temp_file_write_size 256k;
    proxy_max_temp_file_size   512k;
    proxy_temp_path            /mnt/data/tmp/Nginx/proxy_temp;

    open_file_cache max=1000 inactive=20s; 
    open_file_cache_valid    30s; 
    open_file_cache_min_uses 2;
    open_file_cache_errors   on;
  }
}