How to use multi-threading in rails 3?

Question

I am sending mail to the users using actionmailer through postmark. This is my code in controller:

@users = User.where(some condition)
@product = Product.find_by_name(some name).first
for user in @users
  UserMailer.new_product_arrival(user, @product, home_url).deliver
end

and this my user_mailer.rb

def new_product_arrival(user,product,home_url)
  @from         = Settings.mailer_from_address
  @recipients   = user.login
  @sent_on      = Time.now
  @user = user
  @product = product
  @content_type = "text/html"
  @home_url = home_url
end

The problem is that if there are more than 10 users it takes a very long time because of the for loop. I need to know if we can handle this by using multi-threading or background job. I don't want to use background job, but can anyone tell me how to implement the above using multi-threading.

I am using ruby 1.8.7 and rails 3.0.7

Answer 1

There basically two ways to wrap your loop in order to get "multi-threading":

1. Spwan a thread for each delivery and join them back to the main thread

   threads = []
   for user in @users
      threads << Thread.new do
        UserMailer.new_product_arrival(user, @product, home_url).deliver
      end
   end
   threads.each(&:join)
   

2. fork over the entire rails app ( pretty messy but the rails app serving the request will respond immediately ) and have the process detached:

   process = fork do
     for user in @users
       UserMailer.new_product_arrival(user, @product, home_url).deliver
     end
     Process.kill("HUP") 
     #sends the kill signal to current Process, which is the Rails App sending your emails 
   end
   Process.detach(process)
   

Hope that helps

Answer 2

our developer Artem recently made a major update to the Postmark gem

which allows you to send emails easily in batches, which should allow you to send emails faster. Check it out.

Answer 3

Try delayed_job gem. This is a database-based background job gem. We used it in an e-commerce website, for example, sending order confirmation emails to users.

These tasks can happen asynchronously in the background, because your Rails app doesn't need them executed immediately.

Answer 4

um im a rails student from nairobi dev school kenya ..and i think you can give this a try ,..soo what you are having there is the delayed response due to the number of users ..you can try long polling an example

poll = function (){
  s.ajax{
       url:/'chat.json'
       data: { last_time: get last_time () }
     }}.done(function(data) {
     // handle data
     setTimeout(poll,1000);
     });
}

try that in your ow way ..this is useful for a real time application..o you can use even action controller:: live ..i think youre farmiliar with threading with rails .also .the above exmples will hep you ,,hopefuly \