Rails execute script as background job

Question

I've a ruby script that has been implemented as an independent functionality. Now I would like to execute this script in my rails environament, with the added difficulty of executing it as a background job, because it needs a great amount of time processing.

After adding the delayed_job gem, I've tryied calling the following sentence:

delay.system("ruby my_script.rb")

And this is the error I get:

Completed 500 Internal Server Error in 95ms
TypeError (can't dump anonymous module: #<Module:0x007f8a9ce14dc0>):
   app/controllers/components_controller.rb:49:in `create'

Jef · Accepted Answer · 2012-11-13 11:06:38Z

4

Calling the self.delay method from your controller won't work, because DJ will try to serialize your controller into the Job. You'd better create a class to handle your task then flag its method as asynchronous :

class AsyncTask
  def run
    system('ruby my_script.rb')
  end
  handle_asynchronously :run
end

In your controller :

def create
    ...
    AsyncTask.new.run
    ...
end

See the second example in the "Queing Jobs" section of the readme.

answered Nov 13, 2012 at 11:06

Jef

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8 Comments

user1573607 Over a year ago

Ok, and how can I debug it? Puts or logger are not being effective inside the run method.

Jef Over a year ago

Did you try with Delayed::Worker.logger ?

user1573607 Over a year ago

Delayed::Worker.logger "test log" should write the string in the console, isn't it? It's not working. By the way, I've implemented the async task as Erez post, the method is the same?

Jef Over a year ago

Did you check the log/test.log file ?

user1573607 Over a year ago

There isn't the file. Should I write Delayed::Worker.logger = Rails.logger or using it as logger directly?

|

Erez Rabih · Accepted Answer · 2012-11-13 11:20:42Z

0

Like Jef stated the best solution is to create a custom job. The problem with Jef's answer is that its syntax (as far as I know) is not correct and that's his job handles a single system command while the following will allow you more customization:

# lib/system_command_job.rb
class SystemCommandJob < Struct.new(:cmd)
  def perform
    system(cmd)
  end
end

Note the cmd argument for the Struct initializer. It allows you to pass arguments to your job so the code would look like:

Delayed::Job.enqueue(SystemCommandJob.new("ruby my_script.rb"))

answered Nov 13, 2012 at 11:20

Erez Rabih

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2 Comments

Jef Over a year ago

Erez, (as far as I can tell ;)) handle_asynchronously is correct use whenever "a method should always be run in the background" (quoted from DJ README) I tried to answer with concise code and close to the examples provided by the documentation

user1573607 Over a year ago

Erez, to debug Delayed::Worker.logger is not working, any ideas?

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