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SidekiqUniqueJobs

Join the chat at https://gitter.im/mhenrixon/sidekiq-unique-jobs Build Status Code Climate Test Coverage

Support Me

Want to show me some ❤️ for the hard work I do on this gem? You can use the following PayPal link: https://paypal.me/mhenrixon1. Any amount is welcome and let me tell you it feels good to be appreciated. Even a dollar makes me super excited about all of this.

Introduction

This gem adds unique constraints to sidekiq jobs. The uniqueness is achieved by creating a set of keys in redis based off of queue, class, args (in the sidekiq job hash).

By default, only one lock for a given hash can be acquired. What happens when a lock can't be acquired is governed by a chosen Conflict Strategy strategy. Unless a conflict strategy is chosen

This is the documentation for the master branch. You can find the documentation for each release by navigating to its tag.

Here are links to some of the old versions

Usage

Installation

Add this line to your application's Gemfile:

gem 'sidekiq-unique-jobs'

And then execute:

bundle

Add the middleware

Before v7, the middleware was configured automatically. Since some people reported issues with other gems (see Other Sidekiq Gems) it was decided to give full control over to the user.

NOTE if you want to use the reaper you also need to configure the server middleware.

A full example

Sidekiq.configure_server do |config|
  config.redis = { url: ENV["REDIS_URL"], driver: :hiredis }

  config.client_middleware do |chain|
    chain.add SidekiqUniqueJobs::Middleware::Client
  end

  config.server_middleware do |chain|
    chain.add SidekiqUniqueJobs::Middleware::Server
  end

  SidekiqUniqueJobs::Server.configure(config)
end

Sidekiq.configure_client do |config|
  config.redis = { url: ENV["REDIS_URL"], driver: :hiredis }

  config.client_middleware do |chain|
    chain.add SidekiqUniqueJobs::Middleware::Client
  end
end

Your first worker

The most likely to be used worker is :until_executed. This type of lock creates a lock from when UntilExecutedWorker.perform_async is called until right after UntilExecutedWorker.new.perform has been called.

# frozen_string_literal: true

class UntilExecutedWorker
  include Sidekiq::Worker

  sidekiq_options queue: :until_executed,
                  lock: :until_executed

  def perform
    logger.info("cowboy")
    sleep(1) # hardcore processing
    logger.info("beebop")
  end
end

You can read more about the worker configuration in Worker Configuration below.

Requirements

  • Sidekiq >= 5.0 (>= 5.2 recommended)
  • Ruby:
    • MRI >= 2.5 (>= 2.6 recommended)
    • JRuby >= 9.0 (>= 9.2 recommended)
    • Truffleruby
  • Redis Server >= 3.2 (>= 5.0 recommended)
  • [ActiveJob officially not supported][48]
  • [redis-namespace officially not supported][49]

See [Sidekiq requirements][24] for detailed requirements of Sidekiq itself (be sure to check the right sidekiq version).

Locks

Until Executing

A lock is created when UntilExecuting.perform_async is called. Then it is either unlocked when lock_ttl is hit or before Sidekiq calls the perform method on your worker.

Example worker

class UntilExecuting
  include Sidekiq::Workers

  sidekiq_options lock: :until_executing

  def perform(id)
    # Do work
  end
end

NOTE this is probably not so good for jobs that shouldn't be running simultaneously (aka slow jobs).

The reason this type of lock exists is to fix the following problem: sidekiq/issues/3471

Until Executed

A lock is created when UntilExecuted.perform_async is called. Then it is either unlocked when lock_ttl is hit or when Sidekiq has called the perform method on your worker.

Example worker

class UntilExecuted
  include Sidekiq::Workers

  sidekiq_options lock: :until_executed

  def perform(id)
    # Do work
  end
end

Until Expired

This lock behaves identically to the Until Executed except for one thing. This job won't be unlocked until the expiration is hit. For jobs that need to run only once per day, this would be the perfect lock. This way, we can't create more jobs until one day after this job was first pushed.

Example worker

class UntilExpired
  include Sidekiq::Workers

  sidekiq_options lock: :until_expired, lock_ttl: 1.day

  def perform
    # Do work
  end
end

Until And While Executing

This lock is a combination of two locks (:until_executing and :while_executing). Please see the configuration for Until Executing and While Executing

Example worker

class UntilAndWhileExecutingWorker
  include Sidekiq::Workers

  sidekiq_options lock: :until_and_while_executing,
                  lock_timeout: 2,
                  on_conflict: {
                    client: :log,
                    server: :raise
                  }
  def perform(id)
    # Do work
  end
end

While Executing

Tese locks are put on a queue without any type of locking mechanism, the locking doesn't happen until Sidekiq pops the job from the queue and starts processing it.

Example worker

class WhileExecutingWorker
  include Sidekiq::Workers

  sidekiq_options lock: :while_executing,
                  lock_timeout: 2,
                  on_conflict: {
                    server: :raise
                  }
  def perform(id)
    # Do work
  end
end

NOTE Unless a conflict strategy of :raise is specified, if lock fails, the job will be dropped without notice. When told to raise, the job will be put back and retried. It would also be possible to use :reschedule with this lock.

NOTE Unless this job is configured with a lock_timeout: nil or lock_timeout: > 0 then all jobs that are attempted to be executed will just be dropped without waiting.

There is an example of this to try it out in the myapp application. Run foreman start in the root of the directory and open the url: localhost:5000/work/duplicate_while_executing.

In the console you should see something like:

0:32:24 worker.1 | 2017-04-23T08:32:24.955Z 84404 TID-ougq4thko WhileExecutingWorker JID-400ec51c9523f41cd4a35058 INFO: start
10:32:24 worker.1 | 2017-04-23T08:32:24.956Z 84404 TID-ougq8csew WhileExecutingWorker JID-8d6d9168368eedaed7f75763 INFO: start
10:32:24 worker.1 | 2017-04-23T08:32:24.957Z 84404 TID-ougq8crt8 WhileExecutingWorker JID-affcd079094c9b26e8b9ba60 INFO: start
10:32:24 worker.1 | 2017-04-23T08:32:24.959Z 84404 TID-ougq8cs8s WhileExecutingWorker JID-9e197460c067b22eb1b5d07f INFO: start
10:32:24 worker.1 | 2017-04-23T08:32:24.959Z 84404 TID-ougq4thko WhileExecutingWorker JID-400ec51c9523f41cd4a35058 WhileExecutingWorker INFO: perform(1, 2)
10:32:34 worker.1 | 2017-04-23T08:32:34.964Z 84404 TID-ougq4thko WhileExecutingWorker JID-400ec51c9523f41cd4a35058 INFO: done: 10.009 sec
10:32:34 worker.1 | 2017-04-23T08:32:34.965Z 84404 TID-ougq8csew WhileExecutingWorker JID-8d6d9168368eedaed7f75763 WhileExecutingWorker INFO: perform(1, 2)
10:32:44 worker.1 | 2017-04-23T08:32:44.965Z 84404 TID-ougq8crt8 WhileExecutingWorker JID-affcd079094c9b26e8b9ba60 WhileExecutingWorker INFO: perform(1, 2)
10:32:44 worker.1 | 2017-04-23T08:32:44.965Z 84404 TID-ougq8csew WhileExecutingWorker JID-8d6d9168368eedaed7f75763 INFO: done: 20.009 sec
10:32:54 worker.1 | 2017-04-23T08:32:54.970Z 84404 TID-ougq8cs8s WhileExecutingWorker JID-9e197460c067b22eb1b5d07f WhileExecutingWorker INFO: perform(1, 2)
10:32:54 worker.1 | 2017-04-23T08:32:54.969Z 84404 TID-ougq8crt8 WhileExecutingWorker JID-affcd079094c9b26e8b9ba60 INFO: done: 30.012 sec
10:33:04 worker.1 | 2017-04-23T08:33:04.973Z 84404 TID-ougq8cs8s WhileExecutingWorker JID-9e197460c067b22eb1b5d07f INFO: done: 40.014 sec

Custom Locks

You may need to define some custom lock. You can define it in one project folder:

# lib/locks/my_custom_lock.rb
module Locks
  class MyCustomLock < SidekiqUniqueJobs::Lock::BaseLock
    def execute
      # Do something ...
    end
  end
end

You can refer on all the locks defined in lib/sidekiq_unique_jobs/lock/*.rb.

In order to make it available, you should call in your project startup:

(For rails application config/initializers/sidekiq_unique_jobs.rb or other projects, wherever you prefer)

SidekiqUniqueJobs.configure do |config|
  config.add_lock :my_custom_lock, Locks::MyCustomLock
end

And then you can use it in the jobs definition:

sidekiq_options lock: :my_custom_lock, on_conflict: :log

Please not that if you try to override a default lock, an ArgumentError will be raised.

Conflict Strategy

Decides how we handle conflict. We can either reject the job to the dead queue or reschedule it. Both are useful for jobs that absolutely need to run and have been configured to use the lock WhileExecuting that is used only by the sidekiq server process.

The last one is log which can be be used with the lock UntilExecuted and UntilExpired. Now we write a log entry saying the job could not be pushed because it is a duplicate of another job with the same arguments.

It is possible for locks to have different conflict strategy for the client and server. This is useful for :until_and_while_executing.

sidekiq_options lock: :until_and_while_executing,
                on_conflict: { client: :log, server: :reject }

log

sidekiq_options on_conflict: :log

This strategy is intended to be used with UntilExecuted and UntilExpired. It will log a line about that this is job is a duplicate of another.

raise

sidekiq_options on_conflict: :raise

This strategy is intended to be used with WhileExecuting. Basically it will allow us to let the server process crash with a specific error message and be retried without messing up the Sidekiq stats.

reject

sidekiq_options on_conflict: :reject

This strategy is intended to be used with WhileExecuting and will push the job to the dead queue on conflict.

replace

sidekiq_options on_conflict: :replace

This strategy is intended to be used with client locks like UntilExecuted. It will delete any existing job for these arguments from retry, schedule and queue and retry the lock again.

This is slightly dangerous and should probably only be used for jobs that are always scheduled in the future. Currently only attempting to retry one time.

Reschedule

sidekiq_options on_conflict: :reschedule

This strategy is intended to be used with WhileExecuting and will delay the job to be tried again in 5 seconds. This will mess up the sidekiq stats but will prevent exceptions from being logged and confuse your sysadmins.

Custom Strategies

You may need to define some custom strategy. You can define it in one project folder:

# lib/strategies/my_custom_strategy.rb
module Strategies
  class MyCustomStrategy < SidekiqUniqueJobs::OnConflict::Strategy
    def call
      # Do something ...
    end
  end
end

You can refer to all the strategies defined in lib/sidekiq_unique_jobs/on_conflict.

In order to make it available, you should call in your project startup:

(For rails application config/initializers/sidekiq_unique_jobs.rb for other projects, wherever you prefer)

SidekiqUniqueJobs.configure do |config|
  config.add_strategy :my_custom_strategy, Strategies::MyCustomStrategy
end

And then you can use it in the jobs definition:

sidekiq_options lock: :while_executing, on_conflict: :my_custom_strategy

Please not that if you try to override a default lock, an ArgumentError will be raised.

3 Cleanup Dead Locks

For sidekiq versions < 5.1 a sidekiq_retries_exhausted block is required per worker class. This is deprecated in Sidekiq 6.0

class MyWorker
  sidekiq_retries_exhausted do |msg, _ex|
    digest = msg['lock_digest']
    SidekiqUniqueJobs::Digests.new.delete_by_digest(digest) if digest
  end
end

Starting in v5.1, Sidekiq can also fire a global callback when a job dies: In version 7, this is handled automatically for you. You don't need to add a death handler, if you configure v7 like in Add the middleware you don't have to worry about the below.

Sidekiq.configure_server do |config|
  config.death_handlers << ->(job, _ex) do
    digest = job['lock_digest']
    SidekiqUniqueJobs::Digests.new.delete_by_digest(digest) if digest
  end
end

Debugging

There are several ways of removing keys that are stuck. The prefered way is by using the unique extension to Sidekiq::Web. The old console and command line versions still work but might be deprecated in the future. It is better to search for the digest itself and delete the keys matching that digest.

Sidekiq Web

To use the web extension you need to require it in your routes.

#app/config/routes.rb
require 'sidekiq_unique_jobs/web'
mount Sidekiq::Web, at: '/sidekiq'

There is no need to require 'sidekiq/web' since sidekiq_unique_jobs/web already does this.

To filter/search for keys we can use the wildcard *. If we have a unique digest 'uniquejobs:9e9b5ce5d423d3ea470977004b50ff84 we can search for it by enter *ff84 and it should return all digests that end with ff84.

Reflections (metrics, logging, etc.)

To be able to gather some insights on what is going on inside this gem. I provide a reflection API that can be used.

To setup reflections for logging or metrics, use the following API:

def extract_log_from_job(message, job_hash)
  worker    = job_hash['class']
  args      = job_hash['args']
  lock_args = job_hash['lock_args']
  queue     = job_hash['queue']
  {
    message: message,
    worker: worker,
    args: args,
    lock_args: lock_args,
    queue: queue
  }
end

SidekiqUniqueJobs.reflect do |on|
  on.lock_failed do |job_hash|
    message = extract_log_from_job('Lock Failed', job_hash)
    Sidekiq.logger.warn(message)
  end
end

after_unlock_callback_failed

This is called when you have configured a custom callback for when a lock has been released.

error

Not in use yet but will be used deep into the stack to provide a means to catch and report errors inside the gem.

execution_failed

When the sidekiq processor picks the job of the queue for certain jobs but your job raised an error to the middleware. This will be the reflection. It is probably nothing to worry about. When your worker raises an error, we need to handle some edge cases for until and while executing.

lock_failed

If we can't achieve a lock, this will be the reflection. It most likely is nothing to worry about. We just couldn't retrieve a lock in a timely fashion.

The biggest reason for this reflection would be to gather metrics on which workers fail the most at the locking step for example.

locked

For when a lock has been successful. Again, mostly useful for metrics I suppose.

reschedule_failed

For when the reschedule strategy failed to reschedule the job.

rescheduled

For when a job was successfully rescheduled

timeout

This is also mostly useful for reporting/metrics purposes. What this reflection does is signal that the job was configured to wait (lock_timeout was configured), but we couldn't retrieve a lock even though we waited for some time.

unlock_failed

This is not got, this is worth

unlocked

Also mostly useful for reporting purposes. The job was successfully unlocked.

unknown_sidekiq_worker

The reason this happens is that the server couldn't find a valid sidekiq worker class. Most likely, that worker isn't intended to be processed by this sidekiq server instance.

Show Locks

Locks

Show Lock

Lock

Testing

Validating Worker Configuration

Since v7 it is possible to perform some simple validation against your workers sidekiq_options. What it does is scan for some issues that are known to cause problems in production.

Let's take a bad worker:

#app/workers/bad_worker.rb
class BadWorker
  sidekiq_options lock: :while_executing, on_conflict: :replace
end

#spec/workers/bad_worker_spec.rb

require "sidekiq_unique_jobs/testing"
#OR
require "sidekiq_unique_jobs/rspec/matchers"

RSpec.describe BadWorker do
  specify { expect(described_class).to have_valid_sidekiq_options }
end

This gives us a helpful error message for a wrongly configured worker:

Expected BadWorker to have valid sidekiq options but found the following problems:
    on_server_conflict: :replace is incompatible with the server process

If you are not using RSpec (a lot of people prefer minitest or test unit) you can do something like:

assert SidekiqUniqueJobs.validate_worker!(BadWorker.get_sidekiq_options)

Uniqueness

This has been probably the most confusing part of this gem. People get really confused with how unreliable the unique jobs have been. I there for decided to do what Mike is doing for sidekiq enterprise. Read the section about unique jobs: Enterprise unique jobs

SidekiqUniqueJobs.configure do |config|
  config.enabled = !Rails.env.test?
end

If you truly wanted to test the sidekiq client push you could do something like below. Note that it will only work for the jobs that lock when the client pushes the job to redis (UntilExecuted, UntilAndWhileExecuting and UntilExpired).

require "sidekiq_unique_jobs/testing"

RSpec.describe Workers::CoolOne do
  before do
    SidekiqUniqueJobs.config.enabled = false
  end

  # ... your tests that don't test uniqueness

  context 'when Sidekiq::Testing.disabled?' do
    before do
      Sidekiq::Testing.disable!
      Sidekiq.redis(&:flushdb)
    end

    after do
      Sidekiq.redis(&:flushdb)
    end

    it 'prevents duplicate jobs from being scheduled' do
      SidekiqUniqueJobs.use_config(enabled: true) do
        expect(described_class.perform_in(3600, 1)).not_to eq(nil)
        expect(described_class.perform_async(1)).to eq(nil)
      end
    end
  end
end

It is recommended to leave the uniqueness testing to the gem maintainers. If you care about how the gem is integration tested have a look at the following specs:

Configuration

Other Sidekiq gems

apartment-sidekiq

It was reported in #536 that the order of the Sidekiq middleware needs to be as follows.

Sidekiq.client_middleware do |chain|
  chain.add Apartment::Sidekiq::Middleware::Client
  chain.add SidekiqUniqueJobs::Middleware::Client
end

Sidekiq.server_middleware do |chain|
  chain.add Apartment::Sidekiq::Middleware::Server
  chain.add SidekiqUniqueJobs::Middleware::Server
end

The reason being that this gem needs to be configured AFTER the apartment gem or the apartment will not be able to be considered for uniqueness

sidekiq-global_id

It was reported in #235 that the order of the Sidekiq middleware needs to be as follows.

For a working setup check the following file.

Sidekiq.client_middleware do |chain|
  chain.add Sidekiq::GlobalId::ClientMiddleware
  chain.add SidekiqUniqueJobs::Middleware::Client
end

Sidekiq.server_middleware do |chain|
  chain.add Sidekiq::GlobalId::ServerMiddleware
  chain.add SidekiqUniqueJobs::Middleware::Server
end

The reason for this is that the global id needs to be set before the unique jobs middleware runs. Otherwise that won't be available for uniqueness.

sidekiq-status

It was reported in #564 that the order of the middleware needs to be as follows.

# Thanks to @ArturT for the correction

Sidekiq.configure_server do |config|
  config.client_middleware do |chain|
    chain.add SidekiqUniqueJobs::Middleware::Client
    chain.add Sidekiq::Status::ClientMiddleware, expiration: 30.minutes
  end

  config.server_middleware do |chain|
    chain.add Sidekiq::Status::ServerMiddleware, expiration: 30.minutes
    chain.add SidekiqUniqueJobs::Middleware::Server
  end

  SidekiqUniqueJobs::Server.configure(config)
end


Sidekiq.configure_client do |config|
  config.client_middleware do |chain|
    chain.add SidekiqUniqueJobs::Middleware::Client
    chain.add Sidekiq::Status::ClientMiddleware, expiration: 30.minutes
  end
end

The reason for this is that if a job is duplicated it shouldn't end up with the status middleware at all. Status is just a monitor so to prevent clashes, leftovers and ensure cleanup. The status middleware should run after uniqueness on client and before on server. This will lead to less surprises.

Global Configuration

The gem supports a few different configuration options that might be of interest if you run into some weird issues.

Configure SidekiqUniqueJobs in an initializer or the sidekiq initializer on application startup.

SidekiqUniqueJobs.configure do |config|
  config.logger = Sidekiq.logger # default, change at your own discretion
  config.debug_lua       = false # Turn on when debugging
  config.lock_info       = false # Turn on when debugging
  config.lock_ttl        = 600   # Expire locks after 10 minutes
  config.lock_timeout    = nil   # turn off lock timeout
  config.max_history     = 0     # Turn on when debugging
  config.reaper          = :ruby # :ruby, :lua or :none/nil
  config.reaper_count    = 1000  # Stop reaping after this many keys
  config.reaper_interval = 600   # Reap orphans every 10 minutes
  config.reaper_timeout  = 150   # Timeout reaper after 2.5 minutes
end

debug_lua

SidekiqUniqueJobs.config.debug_lua #=> false

Turning on debug_lua will allow the lua scripts to output debug information about what the lua scripts do. It will log all redis commands that are executed and also some helpful messages about what is going on inside the lua script.

lock_timeout

SidekiqUniqueJobs.config.lock_timeout #=> 0

Set a global lock_timeout to use for all jobs that don't otherwise specify a lock_timeout.

Lock timeout decides how long to wait for acquiring the lock. A value of nil means to wait indefinitely for a lock resource to become available.

lock_ttl

SidekiqUniqueJobs.config.lock_ttl #=> nil

Set a global lock_ttl to use for all jobs that don't otherwise specify a lock_ttl.

Lock TTL decides how long to wait at most before considering a lock to be expired and making it possible to reuse that lock.

enabled

SidekiqUniqueJobs.config.enabled #=> true

Globally turn the locking mechanism on or off.

logger

SidekiqUniqueJobs.config.logger #=> #<Sidekiq::Logger:0x00007fdc1f96d180>

By default this gem piggybacks on the Sidekiq logger. It is not recommended to change this as the gem uses some features in the Sidekiq logger and you might run into problems. If you need a different logger and you do run into problems then get in touch and we'll see what we can do about it.

max_history

SidekiqUniqueJobs.config.max_history #=> 1_000

The max_history setting can be used to tweak the number of changelogs generated. It can also be completely turned off if performance suffers or if you are just not interested in using the changelog.

This is a log that can be accessed by a lock to see what happened for that lock. Any items after the configured max_history will be automatically deleted as new items are added.

reaper

SidekiqUniqueJobs.config.reaper #=> :ruby

If using the orphans cleanup process it is critical to be aware of the following. The :ruby job is much slower but the :lua job locks redis while executing. While doing intense processing it is best to avoid locking redis with a lua script. There for the batch size (controlled by the reaper_count setting) needs to be reduced.

In my benchmarks deleting 1000 orphaned locks with lua performs around 65% faster than deleting 1000 keys in ruby.

On the other hand if I increase it to 10 000 orphaned locks per cleanup (reaper_count: 10_0000) then redis starts throwing:

BUSY Redis is busy running a script. You can only call SCRIPT KILL or SHUTDOWN NOSAVE. (Redis::CommandError)

If you want to disable the reaper set it to :none, nil or false. Actually, any value that isn't :ruby or :lua will disable the reaping.

SidekiqUniqueJobs.config.reaper = :none
SidekiqUniqueJobs.config.reaper = nil
SidekiqUniqueJobs.config.reaper = false

reaper_count

SidekiqUniqueJobs.config.reaper_count #=> 1_000

The reaper_count setting configures how many orphans at a time will be cleaned up by the orphan cleanup job. This might have to be tweaked depending on which orphan job is running.

reaper_interval

SidekiqUniqueJobs.config.reaper_interval #=> 600

The number of seconds between reaping.

reaper_timeout

SidekiqUniqueJobs.config.reaper_timeout #=> 10

The number of seconds to wait for the reaper to finish before raising a TimeoutError. This is done to ensure that the next time we reap isn't getting stuck due to the previous process already running.

lock_prefix

SidekiqUniqueJobs.config.lock_prefix #=> "uniquejobs"

Use if you want a different key prefix for the keys in redis.

lock_info

SidekiqUniqueJobs.config.lock_info #=> false

Using lock info will create an additional key for the lock with a json object containing information about the lock. This will be presented in the web interface and might help track down why some jobs are getting stuck.

Worker Configuration

lock_info

Lock info gathers information about a specific lock. It collects things like which lock_args where used to compute the lock_digest that is used for maintaining uniqueness.

sidekiq_options lock_info: false # this is the default, set to true to turn on

lock_prefix

Use if you want a different key prefix for the keys in redis.

sidekiq_options lock_prefix: "uniquejobs" # this is the default value

lock_ttl

Lock TTL decides how long to wait at most before considering a lock to be expired and making it possible to reuse that lock.

Starting from v7 the expiration will take place when the job is pushed to the queue.

sidekiq_options lock_ttl: nil # default - don't expire keys
sidekiq_options lock_ttl: 20.days.to_i # expire this lock in 20 days

lock_timeout

This is the timeout (how long to wait) when creating the lock. By default we don't use a timeout so we won't wait for the lock to be created. If you want it is possible to set this like below.

sidekiq_options lock_timeout: 0 # default - don't wait at all
sidekiq_options lock_timeout: 5 # wait 5 seconds
sidekiq_options lock_timeout: nil # lock indefinitely, this process won't continue until it gets a lock. VERY DANGEROUS!!

unique_across_queues

This configuration option is slightly misleading. It doesn't disregard the queue on other jobs. Just on itself, this means that a worker that might schedule jobs into multiple queues will be able to have uniqueness enforced on all queues it is pushed to.

This is mainly intended for Worker.set(queue: :another).perform_async.

class Worker
  include Sidekiq::Worker

  sidekiq_options unique_across_queues: true, queue: 'default'

  def perform(args); end
end

Now if you push override the queue with Worker.set(queue: 'another').perform_async(1) it will still be considered unique when compared to Worker.perform_async(1) (that was actually pushed to the queue default).

unique_across_workers

This configuration option is slightly misleading. It doesn't disregard the worker class on other jobs. Just on itself, this means that the worker class won't be used for generating the unique digest. The only way this option really makes sense is when you want to have uniqueness between two different worker classes.

class WorkerOne
  include Sidekiq::Worker

  sidekiq_options unique_across_workers: true, queue: 'default'

  def perform(args); end
end

class WorkerTwo
  include Sidekiq::Worker

  sidekiq_options unique_across_workers: true, queue: 'default'

  def perform(args); end
end


WorkerOne.perform_async(1)
# => 'the jobs unique id'

WorkerTwo.perform_async(1)
# => nil because WorkerOne just stole the lock

Finer Control over Uniqueness

Sometimes it is desired to have a finer control over which arguments are used in determining uniqueness of the job, and others may be transient. For this use-case, you need to define either a lock_args method, or a ruby proc.

NOTE: The lock_args method need to return an array of values to use for uniqueness check.

NOTE: The arguments passed to the proc or the method is always an array. If your method takes a single array as argument the value of args will be [[...]].

The method or the proc can return a modified version of args without the transient arguments included, as shown below:

class UniqueJobWithFilterMethod
  include Sidekiq::Worker
  sidekiq_options lock: :until_and_while_executing,
                  lock_args_method: :lock_args # this is default and will be used if such a method is defined

  def self.lock_args(args)
    [ args[0], args[2][:type] ]
  end

  ...

end

class UniqueJobWithFilterProc
  include Sidekiq::Worker
  sidekiq_options lock: :until_executed,
                  lock_args_method: ->(args) { [ args.first ] }

  ...

end

It is possible to ensure different types of unique args based on context. I can't vouch for the below example but see #203 for the discussion.

class UniqueJobWithFilterMethod
  include Sidekiq::Worker
  sidekiq_options lock: :until_and_while_executing, lock_args_method: :lock_args

  def self.lock_args(args)
    if Sidekiq::ProcessSet.new.size > 1
      # sidekiq runtime; uniqueness for the object (first arg)
      args.first
    else
      # queuing from the app; uniqueness for all params
      args
    end
  end
end

After Unlock Callback

If you need to perform any additional work after the lock has been released you can provide an #after_unlock instance method. The method will be called when the lock has been unlocked. Most times this means after yield but there are two exceptions to that.

Exception 1: UntilExecuting unlocks and uses callback before yielding. Exception 2: UntilExpired expires eventually, no after_unlock hook is called.

NOTE: It is also possible to write this code as a class method.

class UniqueJobWithFilterMethod
  include Sidekiq::Worker
  sidekiq_options lock: :while_executing,

  def self.after_unlock
   # block has yielded and lock is released
  end

  def after_unlock
   # block has yielded and lock is released
  end
  ...
end.

Communication

There is a Join the chat at https://gitter.im/mhenrixon/sidekiq-unique-jobs for praise or scorn. This would be a good place to have lengthy discuss or brilliant suggestions or simply just nudge me if I forget about anything.

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request

Contributors

You can find a list of contributors over on Contributors