执行作业

Question

我正在使用SQS作为我的ActiveJobs的后端。

我有一个非常简单的工作，在我的模型的after_create回调中发送到队列：

after_create :update_stuff_after_create

初始化一个ActiveJob：

UpdateStuffAfterCreateJob.perform_later(self.id)

作业正确发送到SQS队列。问题是当负责从队列中读取的另一个实例尝试执行作业时，我看到ActiveRecord::RecordNotFound：

class UpdateStuffAfterCreateJob < ActiveJob::Base
  def perform(id)
    publisher_offer_click = MyModel.find(id) # ActiveRecord::RecordNotFound
    my_model.update_stuff
  end
end

看起来该记录存在于发送作业的实例中，但该记录在使用该作业的实例中不存在。

我一直在深入调试，我创建了这个工作：

class TestingEntityExistsJob < ActiveJob::Base
  def perform(id, exists_outside, time_outside_string)
    Rails.logger.info "[TestingEntityExistsJob] #{id}, #{MyModel.last.id}, #{Time.now.strftime("%H:%M:%S.%L")}, #{time_outside_string}, exists: #{MyModel.where(:id => publisher_offer_click_id).exists?}, exists_outside: #{exists_outside}"
  end
end

我在我的模型的after_create中称之为：

TestingEntityExistsJob.perform_later(self.id, MyModel.where(:id => self.id).exists?, Time.now.strftime('%H:%M:%S.%L'))

我有这样奇怪的结果：

[2017-05-05 16:13:12.773] [TestingEntityExistsJob] 30645284, 30645284, 16:13:12.781, 16:13:12.720, exists: true, exists_outside: true
[2017-05-05 16:13:12.773] [TestingEntityExistsJob] 30645281, 30645284, 16:13:12.781, 16:13:12.659, exists: true, exists_outside: true
[2017-05-05 16:13:12.913] [TestingEntityExistsJob] 30645283, 30645284, 16:13:12.929, 16:13:12.838, exists: true, exists_outside: true
[2017-05-05 16:13:12.964] [TestingEntityExistsJob] 30645285, 30645285, 16:13:12.970, 16:13:12.927, exists: true, exists_outside: true
[2017-05-05 16:13:13.368] [TestingEntityExistsJob] 30645286, 30645285, 16:13:13.391, 16:13:13.309, exists: false, exists_outside: true
[2017-05-05 16:13:13.374] [TestingEntityExistsJob] 30645287, 30645285, 16:13:13.391, 16:13:13.339, exists: false, exists_outside: true
[2017-05-05 16:13:13.447] [TestingEntityExistsJob] 30645288, 30645288, 16:13:13.453, 16:13:13.411, exists: true, exists_outside: true
[2017-05-05 16:13:13.718] [TestingEntityExistsJob] 30645289, 30645289, 16:13:13.723, 16:13:13.658, exists: true, exists_outside: true
[2017-05-05 16:13:14.702] [TestingEntityExistsJob] 30645290, 30645290, 16:13:14.722, 16:13:14.642, exists: true, exists_outside: true
[2017-05-05 16:13:14.842] [TestingEntityExistsJob] 30645291, 30645291, 16:13:14.850, 16:13:14.789, exists: true, exists_outside: true
[2017-05-05 16:13:17.658] [TestingEntityExistsJob] 30645292, 30645292, 16:13:17.663, 16:13:17.599, exists: true, exists_outside: true
[2017-05-05 16:13:18.558] [TestingEntityExistsJob] 30645294, 30645294, 16:13:18.565, 16:13:18.513, exists: true, exists_outside: true
[2017-05-05 16:13:18.648] [TestingEntityExistsJob] 30645293, 30645294, 16:13:18.652, 16:13:18.592, exists: false, exists_outside: true
[2017-05-05 16:13:19.565] [TestingEntityExistsJob] 30645295, 30645295, 16:13:19.570, 16:13:19.514, exists: true, exists_outside: true
[2017-05-05 16:13:21.899] [TestingEntityExistsJob] 30645296, 30645295, 16:13:21.918, 16:13:21.771, exists: false, exists_outside: true
[2017-05-05 16:13:21.916] [TestingEntityExistsJob] 30645297, 30645295, 16:13:21.923, 16:13:21.832, exists: false, exists_outside: true
[2017-05-05 16:13:22.541] [TestingEntityExistsJob] 30645298, 30645298, 16:13:22.547, 16:13:22.484, exists: true, exists_outside: true
[2017-05-05 16:13:23.223] [TestingEntityExistsJob] 30645299, 30645299, 16:13:23.228, 16:13:23.171, exists: true, exists_outside: true

您可以从外部始终查看记录exists，但不总是在作业执行内部。有些时候MyModel.last.id小于我要加载的记录的id。

有关为何会发生这种情况的任何建议吗？我做错了什么？

Answer 1

此行为的原因是after_create在提交save的事务时触发。这会导致作业数据库连接无法访问记录的短暂时间段，因为模型的数据库连接尚未提交。

您想要使用

after_commit :some_method, on: [:create]

而不是

after_create :some_method

https://apidock.com/rails/ActiveRecord/Transactions/ClassMethods/after_commit