最近我们将Rails应用程序迁移到了MRI 2.2.0（可能与此无关），我们遇到了Unicorn零宕机重启的问题。
当我发送USR2信号到主进程（在本例中是PID 19216）时，我在独angular兽日志中得到以下信息：
I, [2015-03-11T23:47:33.992274 #6848] INFO -- : executing ["/srv/ourapp/shared/bundle/ruby/2.2.0/bin/unicorn", "/srv/ourapp/current/config.ru", "-Dc", "/srv/ourapp/shared/config/unicorn.rb", {10=>#<Kgio::UNIXServer:/srv/ourapp/shared/sockets/unicorn.sock>}] (in /srv/ourapp/releases/a0e8b5df474ad5129200654f92a76af00a750f47) I, [2015-03-11T23:47:36.504235 #6848] INFO -- : inherited addr=/srv/ourapp/shared/sockets/unicorn.sock fd=10 /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/lib/unicorn/http_server.rb:206:in `pid=': Already running on PID:19216 (or pid=/srv/ourapp/shared/pids/unicorn.pid is stale) (ArgumentError) from /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/lib/unicorn/http_server.rb:134:in `start' from /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/bin/unicorn:126:in `<top (required)>' from /srv/ourapp/shared/bundle/ruby/2.2.0/bin/unicorn:23:in `load' from /srv/ourapp/shared/bundle/ruby/2.2.0/bin/unicorn:23:in `<main>' E, [2015-03-11T23:47:36.519549 #19216] ERROR -- : reaped #<Process::Status: pid 6848 exit 1> exec()-ed E, [2015-03-11T23:47:36.520296 #19216] ERROR -- : master loop error: Already running on PID:19216 (or pid=/srv/ourapp/shared/pids/unicorn.pid is stale) (ArgumentError) E, [2015-03-11T23:47:36.520496 #19216] ERROR -- : /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/lib/unicorn/http_server.rb:206:in `pid=' E, [2015-03-11T23:47:36.520650 #19216] ERROR -- : /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/lib/unicorn/http_server.rb:404:in `reap_all_workers' E, [2015-03-11T23:47:36.520790 #19216] ERROR -- : /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/lib/unicorn/http_server.rb:279:in `join' E, [2015-03-11T23:47:36.520928 #19216] ERROR -- : /srv/ourapp/shared/bundle/ruby/2.2.0/gems/unicorn-4.8.1/bin/unicorn:126:in `<top (required)>' E, [2015-03-11T23:47:36.521115 #19216] ERROR -- : /srv/ourapp/shared/bundle/ruby/2.2.0/bin/unicorn:23:in `load' E, [2015-03-11T23:47:36.521254 #19216] ERROR -- : /srv/ourapp/shared/bundle/ruby/2.2.0/bin/unicorn:23:in `<main>' 而且当我检查的时候，的确有unicorn.pid和unicorn.pid.oldbin，都包含19216。
什么可能导致这种情况出现？
这是我们的unicorn.rb FWIW：
# Set your full path to application. app_path = "/srv/ourapp/current" # Set unicorn options worker_processes 3 preload_app true timeout 30 listen "/srv/ourapp/shared/sockets/unicorn.sock", :backlog => 64 # Spawn unicorn master worker for user deploy (group: deploy) user 'deploy', 'deploy' # Fill path to your app working_directory app_path # Should be 'production' by default, otherwise use other env rails_env = ENV['RAILS_ENV'] || 'production' # Log everything to one file stderr_path "/srv/ourapp/shared/log/unicorn.log" stdout_path "/srv/ourapp/shared/log/unicorn.log" # Set master PID location pid "/srv/ourapp/shared/pids/unicorn.pid" before_exec do |server| ENV["BUNDLE_GEMFILE"] = "#{app_path}/Gemfile" end before_fork do |server, worker| ActiveRecord::Base.connection.disconnect! sleep 10 old_pid = "#{server.config[:pid]}.oldbin" if File.exists?(old_pid) && server.pid != old_pid begin Process.kill("QUIT", File.read(old_pid).to_i) rescue Errno::ENOENT, Errno::ESRCH # someone else did our job for us end end end after_fork do |server, worker| ActiveRecord::Base.establish_connection Sidekiq.configure_client do |config| config.redis = { namespace: 'sidekiq' } end end