Monkey patch activerecord-3.0.9/lib/active_record/railties/databases.rake enables parallel_tests to work on my PG Jenkins CI

databases.rake

# #{Rails.root}/lib/tasks/databases.rake
=begin
  Monkey Patch 
  activerecord-3.0.9/lib/active_record/railties/databases.rake
  clears obstinate stale PG session to get parallel_tests working
  also, PG user must be superuser to use these low level PG functions
=end
def drop_database(config)
  case config['adapter']
  when /mysql/
    ActiveRecord::Base.establish_connection(config)
    ActiveRecord::Base.connection.drop_database config['database']
  when /sqlite/
    require 'pathname'
    path = Pathname.new(config['database'])
    file = path.absolute? ? path.to_s : File.join(Rails.root, path)

    FileUtils.rm(file)
  when /postgresql/
    ActiveRecord::Base.connection.select_all("select * from pg_stat_activity order by procpid;").each do |x|
      if config['database'] == x['datname'] && x['current_query'] =~ /<IDLE>/
        ActiveRecord::Base.connection.execute("select pg_terminate_backend(#{x['procpid']})")
      end
    end
    ActiveRecord::Base.establish_connection(config.merge('database' => 'postgres', 'schema_search_path' => 'public'))
    ActiveRecord::Base.connection.drop_database config['database']
  end
end

Thanks for the gist! To get this to work with the standalone db:drop task, you can also add:

Rake::Task['environment'].invoke

to the beginning of the method. Otherwise, just invoke the command with:

rake environment db:drop