I am trying to schedule an email to be sent with a delay after an action is triggered. I'm using Action Mailer with the deliver_later functionality :
UserMailer.email_form(params[:session][:email]).deliver_later(wait: 2.minute)
It works fine locally and on heroku, except if I restart the server/deploy again while an email is scheduled but hasn't been sent. How do I get around this?
I think the problem is: deliver_later uses ActiveJob (a part/framework of Rails) under the hood to send emails in background. Rails by default comes with an async queue implementation that runs jobs with an in-process thread pool. Jobs will run asynchronously, but any jobs in the queue will be dropped upon restart or process crashes, because they are only in RAM (memory), but not in a persistent backend (DB, Redis).
You should switch to a different adapter (Sidekiq, Resque, Delayed Job, ...) if you want your jobs to be persisted.
You can find more details here.
Related
i'm interested in running a rails app with sidekiq, and without active job. i find that if active job is there, people get confused if they should use active job apis or sidekiqs, and i want to use sidekiq's apis exclusively for performance reasons.
does current versions of sidekiq (i.e. version 7) support active mailer without active job's deliver_later? i think the historical way to do this was through "delayed extensions" but i see now this has been removed in sidekiq 7:
Delayed extensions provide a very easy and simple way to make method calls asynchronous. By default, all class methods and ActionMailer deliveries can be performed asynchronously.
They were disabled in Sidekiq 5 and removed in Sidekiq 7.
https://github.com/mperham/sidekiq/wiki/Delayed-Extensions
so given that, is there a recommended way to use action mailer with sidekiq and without active job these days?
I've used this instructions and sent "Welcome" mail to my signed up user. But this makes the user wait for 5-8 seconds because the server is trying to complete this mail thing.
I don't want the user to wait until the mail is sent but immediately see the "Mail has sent" message. So this brings me background jobs in Rails.
There are many options like delayed_job, Resque etc for background jobs in Rails. But to use these kind of solutions, as I understand:
1- Create a background job
2- Run this job
Let's say I used one of the background job solutions, so then I need something else to run also this job, like cron job...
I think just for sending sign-up and password reminder emails, another easier solution should be possible. I mean like another external service that 1- I'll create a template for each kind of mail I'll send, 2- I'll pass some arguments like receiver_email, template_id, receiver_username, password_link etc... With that way, I won't need any background job, and the user will not wait.
I came across some other gem called "sucher_punch" but as I understand from the people's messages and posted problems, with using heroku, this gem can fail for some reasons of heroku dynos and the mail may not be sent, and you don't know it.
Anyway, what is the general way that rails developers handle this email issue? Maybe I can also use sendgrid like the way I explained above, can I ?
Sending emails in the background is such a common use case, Rails 4.2 introduced a #deliver_later method in ActionMailer to provide seamless ActiveJob integration.
You don't need to set up a cron job to check if there are any jobs in the background queue. Sidekiq, Resque or DelayedJob will take care of that for you.
It seems Sendgrid does allow creating templates and sending variable content to fill them up, but that feature doesn't undermine the benefits of making that call asynchronously. In fact, deferring it to the background also has the added benefit of not disrupting user experience if the external resource(Sendgrid) is unavailable.
You should try installing one of the background processing solutions you mentioned(I recommend sidekiq) and take advantage of the ActionMailer + ActiveJob integration.
I have an application that needs to occasionally send an email blast to the entire user base when an admin does something. This was working fine, but when there are a lot of users, the page for the admin will wait until all the mail is sent, which is undesirable.
To mitigate this, I tried sending email in a new thread:
t = Thread.new do
User.all.each do |user|
Mailer.email(user).deliver
end
end
at_exit{ t.join }
This worked fine, but then in my test suite, I can't test to ensure the email sending works:
# This test now fails with the new Thread above
test "admin action should send email blast" do
assert_difference("ActionMailer::Base.deliveries.count", User.count) do
post :action
end
end
So my questions are:
Is this method the best way to send email in a new Thread? Or is there a gem available that handles this kind of interaction?
How can I test that the emails are sent in my test suite if the sending is done in a new thread? Is there a way to check to wait for all threads to finish?
In rails 4.2 there's a special class that handles jobs called ActiveJob, active job allows you to queue long tasks for another process to handle them in the background, also you can queue tasks for a certain time, like for example "send this email tomorrow at 8 am".
For these queues to get handled you need to choose a backend to handle them, here's a list of backends that support ActiveJob
Each has it's pros and cons, sidekiq for example is a multithread handler, so it uses lower memory, while for example sucker punch uses the same thread as the main server, so it uses a lot less memory, suitable if you have a low memory server that can't handle a second ruby thread.
As for the testing part, rails guide already explains how to test your emails and test things like if emails has been queued or not, and test that the right template was rendered, and if it contains the right text.
I think you want to send mail asynchronously, For that you may use many gems like - delayed jobs, sidekiq etc. I would personally recommend to use sidekiq as its faster and used Redis in memory db behind the scene.
With Rails 4.2, Active jobs are introduced, so using it has advantage that you can switch from one queuing system to other without having any worry at any time and you can specify which queing machinery yiu want like
module YourApp
class Application < Rails::Application
# Be sure to have the adapter's gem in your Gemfile
# and follow the adapter's specific installation
# and deployment instructions.
config.active_job.queue_adapter = :sidekiq
end
end
I prefer using a queue based approach for async tasks. [Delayed job] (https://github.com/collectiveidea/delayed_job) is one option, but I prefer using [sidekiq] (http://sidekiq.org).
[Here] (http://blog.remarkablelabs.com/2013/01/using-sidekiq-to-send-emails-asynchronously) is an example of sending emails asynchronously using sidekiq.
Best way to send emails in separate threads is to use delayed jobs or similar gem.
https://github.com/collectiveidea/delayed_job
With delayed jobs gem, you can also send emails or do something else in different threads at scheduled time.
Another option is to use sidekiq, install sidekiq gem and add this line to application.rb file
config.active_job.queue_adapter = :sidekiq
I am building a medication reminder system using Ruby on Rails to be deployed on heroku.
Using this system a doctor will enter a patient's medication details including medication name, dose as well as timing details and the app will then notify the patient via sms when its time to take his/her medicine.
I have developed the application but I am stuck on the sms part since that involves running a process over and over again until the medication's period has elapsed.
I want to be able to run a script from a rails app that will repeatedly query the database and when it is time to send a sms it will dispatch it to the patient. This cannot function in the normal request/response web cycle.
I explored rubygems that allow developers to create background jobs such as rufus scheduler and resque but I can't seem to figure out how to go about doing this.
Please help I am open to all types of suggestions. I am using Twilio for sending sms
I don't know about resque/rufus, but I know that sidekiq has the ability to queue jobs, but have them delayed till a certain time.
https://github.com/mperham/sidekiq/wiki/Delayed-Extensions#advanced-options
You'd need to look into how exact the delay is (ie. what sidekiq's polling frequency is) depending on your needs, but I would suspect this would work well.
It would require another dynamo or whatever heroku calls it these days.
I use delayed_job using the run_at param to send scheduled SMS via Twilio from Heroku.
I have a send_message method on my message model that does the actual send with the Twilio API. I chose to create a custom job with Delayed Job so when I schedule the message:
Delayed::Job.enqueue my_custom_job, :run_at => TIME_I_WANT_TO_SEND
Using a the heroku worker to run the background task of sending has been very reliable.
Since you're deploying to Heroku, reading their documentation about scheduling jobs is a must for you:
https://devcenter.heroku.com/articles/scheduler
The gem named Delayed Job (https://github.com/collectiveidea/delayed_job) can do many things in background. But can it run a Rails controller in background so that it still will respond to HTTP requests and return results?
No, this would require Delayed Job to spin up a server. This does not work because a server is already running with your App.
What exactly are you trying to archive? If you have your Rails app running, it will be able to respond to HTTP requests that might come.