Simple Asynchronous Job Scheduler for Rails.
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Asynchronous Job Scheduler for Rails.

The purpose of this gem is to integrate job schedule into Service Domain.

Because of it, this gem uses ActiveRecord model as definition of job schedule.


Add this line to your application's Gemfile:

gem 'crono_trigger'

And then execute:

$ bundle

Or install it yourself as:

$ gem install crono_trigger

Update from v0.3.x

Create crono_trigger system tables

$ rails g crono_trigger:install # => create migrations
$ rake db:migrate

Add locked_by:string column to CronoTrigger::Schedulable model

$ rails g migration add_locked_by_column_to_your_model
$ rake db:migrate
class AddLockedByColumnToYourModel < ActiveRecord::Migration[5.2]
  def change
    add_column :your_models, :locked_by, :string


Execute crono_trigger:model generator.

$ rails g crono_trigger:model mail_notification
      create  db/migrate/20170619064928_create_mail_notifications.rb
      create  app/models/mail_notification.rb
      # ...

Migration sample

class CreateMailNotifications < ActiveRecord::Migration
  def change
    create_table :mail_notifications do |t|

      # columns for CronoTrigger::Schedulable
      t.string    :cron
      t.datetime  :next_execute_at
      t.datetime  :last_executed_at
      t.integer   :execute_lock, limit: 8, default: 0, null: false
      t.datetime  :started_at, null: false
      t.datetime  :finished_at
      t.string    :last_error_name
      t.string    :last_error_reason
      t.datetime  :last_error_time
      t.integer   :retry_count, default: 0, null: false

    add_index :mail_notifications, [:next_execute_at, :execute_lock, :started_at, :finished_at], name: "crono_trigger_index_on_mail_notifications"

Implement #execute method

class MailNotification < ActiveRecord::Base
  include CronoTrigger::Schedulable

  self.crono_trigger_options = {
    retry_limit: 5,
    retry_interval: 10,
    exponential_backoff: true,
    execute_lock_timeout: 300,

  # `execute`, `retry` callback is defined
  # can use `before_execute`, `after_execute`, `around_execute`
  # `before_retry`, `after_retry`, `around_retry`

  # If execute method raise Exception, worker retry task until reach `retry_limit`
  # If `retry_count` reaches `retry_limit`, task schedule is reset.
  # If record has cron value, reset process set next execution time by cron definition
  # If record has no cron value, reset process clear next execution time
  def execute

    throw :retry # break execution and retry task
    throw :abort # break execution and raise AbortExecution. AbortExecution is not retried
    throw :ok    # break execution and handle task as success
    throw :ok_without_reset    # break execution and handle task as success but without schedule reseting and unlocking

# one time schedule
MailNotification.create(next_execute_at: Time.current.since(5.minutes))

# cron schedule
MailNotification.create(cron: "0 12 * * *").activate_schedule!
# or "0 12 * * *").activate_schedule!.save

# if update cron column or timezone column
# update next_execute_at automatically by before_update callback
mail = MailNotification.create(cron: "0 12 * * *").activate_schedule!
mail.next_execute_at # => next 12:00 with
mail.update(cron: "0 13 * * *")
mail.next_execute_at # => next 13:00 with
mail.update(timezone: "Asia/Tokyo")
mail.next_execute_at # => next 13:00 with Asia/Japan

Run Worker

$ crono_trigger MailNotification
$ crono_trigger --help
Usage: crono_trigger [options] MODEL [MODEL..]
    -f, --config-file=CONFIG         Config file (ex. ./crono_trigger.rb)
    -e, --environment=ENV            Set environment name (ex. development, production)
    -p, --polling-thread=SIZE        Polling thread size (Default: 1)
    -i, --polling-interval=SECOND    Polling interval seconds (Default: 5)
    -c, --concurrency=SIZE           Execute thread size (Default: 25)
    -l, --log=LOGFILE                Set log output destination (Default: STDOUT or ./crono_trigger.log if daemonize is true)
        --log-level=LEVEL            Set log level (Default: info)
    -d, --daemonize                  Daemon mode
        --pid=PIDFILE                Set pid file
    -h, --help                       Prints this help



name type required rename description
cron string no no Recurring schedule formatted by cron style
next_execute_at datetime yes yes Timestamp of next execution. Worker executes task if this column <= now
last_executed_at datetime no yes Timestamp of last execution
timezone datetime no yes Timezone name (Parsed by tzinfo)
execute_lock integer yes yes Timestamp of fetching record in order to hide record from other transaction during execute lock timeout.
when execution complete this column is reset to 0
started_at datetime no yes Timestamp of schedule activated
finished_at datetime no yes Timestamp of schedule deactivated
last_error_name string no no Class name of last error
last_error_reason string no no Error message of last error
last_error_time datetime no no Timestamp of last error occured
retry_count integer no no Retry count.
If execution succeed retry_count is reset to 0

You can rename some columns. ex. crono_trigger_options[:next_execute_at_column_name] = "next_time"

Admin Web


Standalone mode

$ crono_trigger-web --rails

Mount as Rack app

# config/routes.rb
require "crono_trigger/web"
mount CronoTrigger::Web => '/crono_trigger'

Rollbar integration

This gem has rollbar plugin. If crono_trigger/rollbar is required, Add Rollbar logging process to CronoTrigger.config.error_handlers


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at


The gem is available as open source under the terms of the MIT License.