My Rails cron job:
every 3.hours do
runner "MyModel.some_process"
rake "my:rake:task"
command "/usr/bin/my_great_command"
end
I only want this triggered when an attribute in MyModel is set to true and stop when it is set to false.
For triggered when an attribute (e.g. availability) in MyModel set to true and stop if it is set to be false, You need to create a method in MyModel like this -
def other_process
if attr
MyModel.some_process
rake "my:rake:task"
command "/usr/bin/my_great_command"
end
end
every 3.hours do
MyModel.other_process
end
The new Rails Active Job is designed for this very use case.
Active Job is a framework for declaring jobs and making them run on a variety of queuing backends. These jobs can be everything from regularly scheduled clean-ups, to billing charges, to mailings. Anything that can be chopped up into small units of work and run in parallel, really.
http://edgeguides.rubyonrails.org/active_job_basics.html
Related
I am working on an event app, that showcases the events near my area.
A Boolean is_weekly_event is set for each entry.
If it is set to true I need to show that event in my app every week on the same data and time.
Therefore, I need to write a cron job, that re-creates this event every time it passes it's end_time, for the same time next week!
Thanks in advance!
you can use whenever gem to add cron job. I have used this in one of my projects and works very fine.
You can define rake tasks in lib/ and in your schedule.rb file which will be generated when you will do whenervize your project.
every 3.hours do # 1.minute 1.day 1.week 1.month 1.year is also supported
# your task here
end
every 1.day, :at => '4:30 am' do
# your task here
end
After finishing all you need is to update your crontab file for your machine using this command.
$ whenever --update-crontab
Note - just a take care to load proper environment(dev, prod) for the rake tasks, it took me hard to find out when i was trying to run the cron.
Thanks
I am on Rails 4 using the Resque Scheduler gem.
I am also using the sitemap generator gem in order to dynamically generate my sitemap.
I am having trouble figuring out the best way to schedule a rake task with resque scheduler. The sitemap generator recommends whenever, but I am assuming resque scheduler can accomplish the same thing (don't want to install another gem if I don't have to).
Does anyone know how to set this up?
I would like to run rake sitemap:refresh:no_ping every 5 hours.
I was thinking I would just schedule a background job and run it from there:
# resque_schedule.yml
update_sitemap:
every: 5h
class: "SitemapUpdater"
description: "This job refreshes the sitemap"
# sitemap_updater.rb
class SitemapUpdater
#queue = :sitemap_queue
def self.perform
# run rake task here
end
end
... however, I'm not sure if this is a good practice. Any advice would be much appreciated.
I don't see a problem with your approach, you just must be aware that the scheduler is reset during every deployment, so if you do frequent deploys, your scheduled jobs might be run later or even not run at all, as documented:
IMPORTANT: Rufus every syntax will calculate jobs scheduling time starting from the moment of deploy, resulting in resetting schedule time on every deploy, so it's probably a good idea to use it only for frequent jobs (like every 10-30 minutes), otherwise - when you use something like every 20h and deploy once-twice per day - it will schedule the job for 20 hours from deploy, resulting in a job to never be run.
You might also run the rake from system cron itself, which is an even more lightweight solution as it requires no scheduler gems at all, just the rake task, and will be scheduled reliably in time.
See e.g. this answer for setting up the "every 5 hours" frequency in crontab and you might also need to study RVM wrappers if you use RVM for your ruby project (you must call rake using the RVM wrappers in such case, e.g. call /home/deploy/.rvm/wrappers/ruby-2.3.0#mygemset/rake instead of just rake).
Task:
Delete an item in Async manner [HomeWork]
I have already configured Active jobs with delayed_jobs in my rails application but I am still confused about performing Async task in rails project.
Let's take an example:
I have some item to delete from the database but I want to do it in Async manner. I also read about perform_later or perform_now method in delayed_job blogs. Here is my code which is working fine:
Controller class
def destroy
PostJob.perform_now(params[:id])
respond_to do |format|
format.xml { head :ok }
format.js { render 'posts.js.erb' }
end
end
Job class
class PostJob < ActiveJob::Base
queue_as :default
def perform(id)
#post = Post.find(id)
#post.destroy
end
end
According to official doc of delayed_jobs I can add handle_asynchronously in the end of method to run in async manner. How can I implement in this case?
My Question:
When I am looking at destroy method it is not deleting the element in Async way. However every steps written in destroy method is in Synchronous. Am I wrong?
If it's not then How can I implement destroy method to delete post in async manner?
Backgrounding task and cron job are same thing?
Edit -1
After giving suggestion by A Fader Darkly, I changed perform_now to perform_later which is working perfectly for Async process but it is not deleting the entry from table (code is fine because it works when i user perform_now).
Also when I am running job manually by following command, Everything works fine:
rake jobs:work
Is there any way to execute delay_job task as soon as the queue get some new data?
If you change your destroy method to call:
PostJob.perform_later(params[:id])
it should happen asynchronously. If not, you have some more set-up to do.
For your questions:
Yes you are right, but what you say is a tautology. Everything in that method is synchronous - the job queue isn't used because of the perform_now. Thus destroy isn't deleting in an async way.
See above.
Cron jobs work on the operating system level and are scheduled regularly for particular times. You could have a cron job working every minute, for example, or every day, or week (on a particular day at a particular time). They run from a schedule file called a crontab.
'Backgrounding' a task simply stops it from taking over the IO of your terminal session. So you can carry on using the terminal while the process runs in the background. Generally this is done on an ad-hoc basis, so you don't have to wait for a heavy operation to complete before going on to do different tasks.
EDIT
Based on edits to the question, it sounds like Delayed Job daemon needs to be started. From the instructions:
Note: For Rails 4 replace script/delayed_job with bin/delayed_job
When running a queue locally, omit the 'RAILS_ENV=production' part of commands.
Running Jobs
script/delayed_job can be used to manage a background process which will start working off jobs.
To do so, add gem "daemons" to your Gemfile and make sure you've run rails generate delayed_job.
You can then do the following:
RAILS_ENV=production script/delayed_job start
RAILS_ENV=production script/delayed_job stop
Runs two workers in separate processes.
RAILS_ENV=production script/delayed_job -n 2 start
RAILS_ENV=production script/delayed_job stop
Set the --queue or --queues option to work from a particular queue.
RAILS_ENV=production script/delayed_job --queue=tracking start
RAILS_ENV=production script/delayed_job --queues=mailers,tasks start
Use the --pool option to specify a worker pool. You can use this option multiple times to start different numbers of workers for different queues.
The following command will start 1 worker for the tracking queue,
2 workers for the mailers and tasks queues, and 2 workers for any jobs:
RAILS_ENV=production script/delayed_job --pool=tracking --pool=mailers,tasks:2 --pool=*:2 start
Runs all available jobs and then exits
RAILS_ENV=production script/delayed_job start --exit-on-complete
or to run in the foreground
RAILS_ENV=production script/delayed_job run --exit-on-complete
I am a beginner when it comes to Rails. I am trying to follow this example:
http://ryanselk.com/2014/09/25/using-background-jobs-in-rails-42-with-active-job/
It says:
"Jobs can be added to the job queue from anywhere. We can add a job to the queue by: ResizeImage.perform_later 'http://example.com/ex.png' "
[UPDATE] Sorry, I am stupid. I came up with this task:
namespace :simple do
# call from command line:
# rake simple:resize_images
desc "Resize images"
task resize_images: :environment do
Dir.foreach('storage') do |next_image|
puts next_image
next if next_image == '.' or next_image == '..'
ResizeImage.perform_later next_image
end
end
end
but now I do:
rake simple:resize_images
and I get:
zacek2_phpP9JGif.jpg
rake aborted!
NameError: uninitialized constant ResizeImage
I've tried:
require ResizeImage
but that did not fix the problem.
I am afraid I don't understand how loading works in Rails. How do I load ResizeImage?
Do I set it up as a cron job?
No.
From the rails guides:
Active Job is a framework for declaring jobs and making them run on a variety of queueing backends.
Active Job is an interface to queueing backends such as sidekiq, delayed_job or resque. It's simply a way for you to write background jobs where you don't have to care about which of the queueing backends will be used.
How do I start ActiveJob?
So ActiveJob doesn't run background jobs on it's own. You're still missing one of the backends. Say you have decided to use delayed_job: Get it installed and then start it via:
script/delayed_job start
I don't understand where "anywhere" is.
That means anywhere in your code, you could write something like:
user.rb
def send_registration_email
UserRegistraionMailJob.perform_later self
end
I have a custom environment called 'reports' that is setup to hit a slave database. I am trying to configure some cron jobs using the Whenever gem and want to test them in development before I deploy. Is there any way to test cron jobs in development? Is there anyway I could schedule them locally and then start my reports server and see if they run? Thank You!
I would start off by reviewing how the gem itself (whenever gem) is conducting their tests. This is an extract from one of their functional test:
context "weekday at a (single) given time" do
setup do
#output = Whenever.cron \
<<-file
set :job_template, nil
every "weekday", :at => '5:02am' do
command "blahblah"
end
file
end
should "output the command using that time" do
assert_match '2 5 * * 1-5 blahblah', #output
end
end