Rails 4.2 rollback transaction

clockworkを使って定期処理を実装したのですが、トランザクションロールバックしてしまいます。どうすれば直るでしょうか？なんのトランザクションがロールバックしているのでしょうか？ちなみにローカル環境下では定期処理自体は動いています。

ログ

 (0.1ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.3ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:10:36.818442') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'
   (0.1ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.3ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:11:36.916917') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'
   (0.2ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.2ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:12:36.602979') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'
   (0.1ms)  begin transaction
   (0.2ms)  rollback transaction
   (0.3ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:13:36.908669') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'
   (0.1ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.4ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:13:44.742769') AND "items"."trade" = 'f' AND "items"."limit_check" = 'f'
   (0.1ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.2ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:14:36.719051') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'
   (0.2ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.2ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:15:36.733665') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'
   (0.3ms)  begin transaction
   (0.1ms)  rollback transaction
   (0.3ms)  SELECT COUNT(*) FROM "items" WHERE "items"."deleted_at" IS NULL AND ("items"."limit_day" BETWEEN '2013-12-24 00:00:00.000000' AND '2015-05-28 17:16:36.400022') AND "items"."trade" = 't' AND "items"."limit_check" = 'f'

lib/tasks/item.rake

namespace :item do
  desc "TODO"
  #アイテムのリミットとトレードチェック取引ナビ作成
  task trade_limit_end_item_check: :environment do


    no_check_item = Item.where(limit_day: Time.mktime(2014, 12, 24, 00, 00, 00).prev_year..Time.now, trade: true, limit_check: false)


    if no_check_item.count > 0
      Item.transaction do
        no_check_item.find_each do |item|

          #該当ユーザ
          warrant = Warrant.find_by(item_id: item.id)


          #取引ナビ生成
          navi = Navi.create(exhibitor_id: item.user_id, proprietor_id: warrant.holder_id, item_id: item.id, status: false, score_judge: true, score_body:'')

          #お知らせ一覧 取引ナビお知らせ
          Todo.create(exhibitor_id: item.user_id, proprietor_id: warrant.holder_id, item_id: item.id, navi_id: navi.id, body_num: 90000, status: false)

          #ループ中のcreateのパフォーマンスも気になるようであれば、activerecord-importというgemを利用する

          #アイテムタイムリミットチェックフラグ
          item.update({limit_check: true, phase: 20000})
        end
      end
    end
  end





  #アイテムタイムリミッチェック
  task limit_day_check: :environment do


    limit_day_end_item = Item.where(limit_day: Time.mktime(2014, 12, 24, 00, 00, 00).prev_year..Time.now, trade: false, limit_check: false)


    if limit_day_end_item.count > 0
      Item.transaction do
        limit_day_end_item.find_each do |item|


          #アイテムタイムリミットチェックフラグ
          item.update({limit_check: true, phase: 10010})

        end
      end
    end
  end
end

lib/clock.rb

require 'clockwork'
include Clockwork

every(60.second, 'trade_limit_end_item_check.job') do
   puts `rake item:trade_limit_end_item_check`
end


every(300.second, 'limit_day_check.job') do
  puts `rake item:limit_day_check`
end