Unicorn stuck in loop: Refreshing Gem list - ruby-on-rails

Question

I'm using Rails 4.0.0, Ruby 2.3 and Unicorn.
My app was working perfectly until the day I tried to add a nem gem in my Gemfile. Everything's working like a charm locally, but when I deploy to DO using Capistrano, I get stuck in a loop with the error:
E, [2016-09-26T11:40:29.801388 #24545] ERROR -- : reaped #<Process::Status: pid 4280 exit 1> worker=0
I, [2016-09-26T11:40:29.802952 #4287] INFO -- : Refreshing Gem list
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/activesupport-4.0.0/lib/active_support/values/time_zone.rb:282: warning: circular argument reference - now
E, [2016-09-26T11:40:32.116762 #4287] ERROR -- : uninitialized constant Vimeo::HTTParty (NameError)
/home/deployer/apps/my_app/releases/20160924171252/app/controllers/webinars_controller.rb:2:in `<class:Vimeo>'
/home/deployer/apps/my_app/releases/20160924171252/app/controllers/webinars_controller.rb:1:in `<top (required)>'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/engine.rb:465:in `block (2 levels) in eager_load!'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/engine.rb:464:in `each'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/engine.rb:464:in `block in eager_load!'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/engine.rb:462:in `each'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/engine.rb:462:in `eager_load!'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/engine.rb:347:in `eager_load!'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/application/finisher.rb:56:in `each'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/application/finisher.rb:56:in `block in <module:Finisher>'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/initializable.rb:30:in `instance_exec'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/initializable.rb:30:in `run'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/initializable.rb:55:in `block in run_initializers'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `call'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
/home/deployer/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/initializable.rb:54:in `run_initializers'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/application.rb:215:in `initialize!'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/railties-4.0.0/lib/rails/railtie/configurable.rb:30:in `method_missing'
/home/deployer/apps/my_app/releases/20160924171252/config/environment.rb:5:in `<top (required)>'
config.ru:4:in `require'
config.ru:4:in `block in <main>'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/rack-1.5.5/lib/rack/builder.rb:55:in `instance_eval'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/rack-1.5.5/lib/rack/builder.rb:55:in `initialize'
config.ru:1:in `new'
config.ru:1:in `<main>'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn.rb:56:in `eval'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn.rb:56:in `block in builder'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn/http_server.rb:752:in `build_app!'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn/http_server.rb:617:in `init_worker_process'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn/http_server.rb:639:in `worker_loop'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn/http_server.rb:508:in `spawn_missing_workers'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn/http_server.rb:519:in `maintain_worker_count'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/lib/unicorn/http_server.rb:283:in `join'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/gems/unicorn-5.1.0/bin/unicorn:126:in `<top (required)>'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/bin/unicorn:23:in `load'
/home/deployer/apps/my_app/shared/bundle/ruby/2.3.0/bin/unicorn:23:in `<top (required)>'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/cli/exec.rb:74:in `load'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/cli/exec.rb:74:in `kernel_load'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/cli/exec.rb:27:in `run'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/cli.rb:332:in `exec'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/vendor/thor/lib/thor/invocation.rb:126:in `invoke_command'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/vendor/thor/lib/thor.rb:359:in `dispatch'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/cli.rb:20:in `dispatch'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/vendor/thor/lib/thor/base.rb:440:in `start'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/cli.rb:11:in `start'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/exe/bundle:34:in `block in <top (required)>'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/lib/bundler/friendly_errors.rb:100:in `with_friendly_errors'
/home/deployer/.rvm/gems/ruby-2.3.0/gems/bundler-1.13.1/exe/bundle:26:in `<top (required)>'
/home/deployer/.rvm/gems/ruby-2.3.0/bin/bundle:23:in `load'
/home/deployer/.rvm/gems/ruby-2.3.0/bin/bundle:23:in `<main>'
/home/deployer/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `eval'
/home/deployer/.rvm/gems/ruby-2.3.0/bin/ruby_executable_hooks:15:in `<main>'
I don't know exactly what's happening, because I can use the code from this new Gem locally but when deployed it don't load, or don't install.
Seems that could be a syntax problem searching on Google, but don't know how to make sure because it was a long time ago I haven't added a Gem, so the syntax erro could be so old. Is there some tool to check if there's a syntax error? And I thing it's weird since it's working locally.
My Gemfile
source 'https://rubygems.org'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.0.0'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 4.0.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier'
# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby
# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
gem 'jquery-turbolinks'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 1.2'
# gem 'anjlab-bootstrap-rails', :require => 'bootstrap-rails', :github => 'anjlab/bootstrap-rails'
gem 'bootstrap-sass', '~> 3.2.0'
gem 'devise'
gem 'paperclip', '~> 3.0'
gem 'aws-sdk', '~> 1'
gem 'nokogiri', '~> 1.5.1'
gem 'wicked_pdf'
# gem "wkhtmltopdf-heroku", :git => 'git://github.com/camdez/wkhtmltopdf-heroku.git'
gem "wkhtmltopdf-binary"
gem 'newrelic_rpm'
gem 'validates_email_format_of'
# gem 'will_paginate', '~> 3.0.6'
gem 'will_paginate-bootstrap'
gem 'iconv'
gem 'roo'
gem 'roo-xls'
gem 'airbrake', '~> 4.3'
gem "paranoia", "~> 2.0"
gem 'ransack'
gem 'omniauth-facebook'
gem 'omniauth-google-oauth2'
gem 'activerecord-session_store', github: 'rails/activerecord-session_store'
gem 'nested_form_fields'
gem 'httparty'
group :doc do
# bundle exec rake doc:rails generates the API under doc/api.
# gem 'sdoc', require: false
end
# Use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'
# Use unicorn as the app server
# Use Capistrano for deployment
group :development do
gem 'sqlite3'
gem 'awesome_print'
gem "capistrano", "~> 3.6"
gem 'capistrano-rails', '~> 1.1'
gem 'capistrano-rvm'
gem 'capistrano3-unicorn'
gem 'capistrano-local-precompile', require: false
end
group :production do
gem 'unicorn'
gem 'pg'
gem 'rails_12factor'
end
# Use debugger
# gem 'debugger', group: [:development, :test]

Answer 1

Similar problem here. It happens when you change you Gemfile, using unicorn:reload doesn't run your new code.
Solved restarting unicorn instead of reloading it.
If you are using Capistrano, change the after deploy trigger from
invoke 'unicorn:reload' to:
invoke 'unicorn:stop'
invoke 'unicorn:start'
According to https://github.com/tablexi/capistrano3-unicorn/issues/45 unicorn:restart is not working properly.

Answer 2

Our problem was that unicorn master process wasn't restarted correctly, because it was killed with:
/bin/kill -s HUP `cat tmp/pids/unicorn.pid`
Which doesn't actually kill the unicorn master process (only reloads the config, see SIGHUP documentation). Verify by running ps -ef | grep 'unicorn'.
Our problem was solved changing the killing of unicorn master process with:
/bin/kill `cat tmp/pids/unicorn.pid`
PS: cat tmp/pids/unicorn.pid just outputs the PID of the unicorn master process.