Using out of band GC via OobGC.

00_unicorn_tweaks.md

Unicorn tweaks

Using out of band GC via OobGC.

Credits

• Out of band GC
• Unicorn::OobGC
• Unicorn Killer gist
• Unicorn Worker Killer gem

Example config.ru

require_dependency 'unicorn/oob_gc'
GC.disable # Don't run GC during requests
use(Unicorn::OobGC, 40) # Only GC once every n requests

# UnicornSlayer kills overgrown workers
require_dependency 'unicorn/unicorn_slayer.rb'
use(UnicornSlayer::MaxRequests, 1000)
use(UnicornSlayer::Oom, 400 * 1024, 1)

# GC ever two requests that hit /expensive/foo or /more_expensive/foo
# in your app.  By default, this will GC once every 5 requests
# for all endpoints in your app
# from http://unicorn.bogomips.org/Unicorn/OobGC.html
use(Unicorn::OobGC, 2, %r{\A/(?:expensive/foo|more_expensive/foo)})

01_unicorn_slayer.rb

# # your config.ru
# require 'unicorn_slayer'
# use UnicornSlayer::MaxRequests, 1000
# use UnicornSlayer::Oom, 400 * 1024

module UnicornSlayer
  module Kill
    def quit
      sec = (Time.now - @process_start).to_i
      warn "#{self.class} send SIGQUIT (pid: #{Process.pid})\talive: #{sec} sec"
      Process.kill :QUIT, Process.pid
    end
  end

  class Oom
    include Kill

    def initialize(app, memory_size= 512 * 1024, check_cycle = 10)
      @app = app
      @memory_size = memory_size
      @check_cycle = check_cycle
      @check_count = 0
    end

    def rss
      `ps -o rss= -p #{Process.pid}`.to_i
    end

    def call(env)
      @process_start ||= Time.now
      if (@check_count += 1) % @check_cycle == 0
        @check_count = 0
        quit if rss > @memory_size
      end
      @app.call env
    end
  end

  class MaxRequests
    include Kill

    def initialize(app, max_requests = 1000)
      @app = app
      @max_requests = max_requests
    end

    def call(env)
      @process_start ||= Time.now
      quit if (@max_requests -= 1) == 0
      @app.call env
    end
  end
end