Tag Archives: Ruby

Avoiding Sidekiq Memory Leaks By Killing It Regularly

Memory leaks are hard to hunt down … but killing things is super easy 🙂
(you have a monitor that restarts them … right !?)

# memory leaks or config changes happen ...
# shutdown -> slowly kill all threads -> restarted by service
# log of all restarts is kept in tmp/shutdown
def trigger_worker_restart_after_interval
  Thread.new do
    interval = 30*60
    time = interval + rand(interval)
    puts "Planning restart in #{time}s -> #{(Time.now + time).to_s(:db)}"

    sleep time
    puts "Planned restart"
    FileUtils.mkdir_p("tmp")
    File.write("tmp/parent_pid", Process.pid)

    # end this thread to ensure a clean exit and kill yourself
    `bundle exec sidekiqctl stop tmp/parent_pid 60 2>&1 >> tmp/shutdown &`
  end
end

Check in your gems Gemfile.lock

Advantages of checking in the Gemfile.lock when developing gems:

  • A known good state to fall back on and do incremental updates
  • Being able to instantly work on an old project
  • No random failures for every new contributor
  • No “Bundler could not find compatible versions for gem” errors when Gemfile changes and users have an old lock

To test against newest versions, add `before_install: rm Gemfile.lock` to .travis.yml … same coverage, less drama.

Transparant redirect for jquery ajax requests in rails with status code 278

There is no perfect backwards compatible solution out there afaik, but this is getting me pretty close to where I want it to be.

  • instead of redirecting set a empty 278 response (made up status code) for xhr requests
  • tell jquery to redirect when receiving a 278 response
  • the success handlers are still executed / there is no way to stop them, but they can either just insert the blank reply or do a != '' check
// application.js
// when we get a fake redirect response, go there
// this will still execute success handlers, but hopefully the fail or are not ugly ...
$.ajaxSetup({
  statusCode: {
    278: function(_,_,response){
      // using turbolinks to not lose back functionality
      Turbolinks.visit(response.getResponseHeader('X-278-redirect'));
    }
  }
})

# some controller
redirect_to_with_xhr signup_path

# application_controller.rb
# ajax requests follow all redirects, so we have to improvise with a
# special code and header to not get placeholders replaced with full pages.
def redirect_to_with_xhr(path)
  if request.xhr?
    response.headers["X-278-redirect"] = path
    head 278
  else
    redirect_to path
  end
end

Print capistrano execution time per server

Are all servers slow or just one ?

Output
Example logging all times > 3 seconds.

executing 'ruby -e "r = rand(10); puts %{sleep #{r}}; sleep r"'
 ** [out :: dbadmin1] sleep 6
 ** [out :: app1] sleep 4
 ** [out :: work1] sleep 2
 ** [out :: mirror1] sleep 5
 ** Server dbadmin1 finished command in 4 seconds
 ** Server app1 finished command in 7 seconds

Code

module PerServerTime
  # set via Capistrano::Command.per_server_time_threshold = 111
  def self.included(base)
    class << base
      attr_accessor :per_server_time_threshold
    end
  end

  # whenever a command finishes on 1 server print how long it ran on this server
  def process_iteration
    return super if @channels.size < 2 # do not need per-server logging for 1 server

    @start_time ||= Time.now.to_f
    @closed_channels ||= []

    @channels.each do |channel|
      if channel[:closed] && !@closed_channels.include?(channel)
        @closed_channels < (self.class.per_server_time_threshold || 30)
          host = channel.connection.instance_variable_get(:@xserver).host
          logger.info("Server #{host} finished command in #{time} seconds")
        end
      end
    end

    super
  end
end

Capistrano::Command.send(:include, PerServerTime)

Omniauth / OAuth integration test with webmock

Took me a while to figure out all the stubs … maybe this is useful later 🙂
I’m using this to test our facebook / twitter signup flows.

def external_redirect(url)
  yield
rescue ActionController::RoutingError # goes to twitter.com/oauth/authenticate
  current_url.must_equal url
else
  raise "Missing external redirect"
end

it "signs up" do
  twitter_id = 12345
  visit "/"
  
  stub_request(:post, "https://api.twitter.com/oauth/request_token").
    to_return(body: "oauth_token=TOKEN&oauth_token_secret=SECRET&oauth_callback_confirmed=true")

  external_redirect "https://api.twitter.com/oauth/authenticate?x_auth_access_type=read&oauth_token=TOKEN" do
    click_link "Continue with Twitter"
  end

  # https://dev.twitter.com/oauth/reference/post/oauth/access_token
  stub_request(:post, "https://api.twitter.com/oauth/access_token").
    to_return(body: "oauth_token=TOKEN&oauth_token_secret=SECRET&user_id=#{twitter_id}&screen_name=twitterapi")

  # https://dev.twitter.com/rest/reference/get/account/verify_credentials
  stub_request(:get, "https://api.twitter.com/1.1/account/verify_credentials.json?include_entities=false&skip_status=true").
    to_return(body: %{{"profile_image_url_https": "image_normal.png"}})

  visit "/auth/twitter/callback"
end