View Source Oban (Oban v2.13.5)

Oban is a robust job processing library which uses PostgreSQL for storage and coordination.

installation

Installation

See the installation guide for details on installing and configuring Oban in your application.

requirements

Requirements

Oban requires Elixir 1.11+, Erlang 21+, and PostgreSQL 10.0+.

defining-workers

Defining Workers

Worker modules do the work of processing a job. At a minimum they must define a perform/1 function, which is called with an %Oban.Job{} struct.

Note that the args field of the job struct will always have string keys, regardless of the key type when the job was enqueued. The args are stored as jsonb in PostgreSQL and the serialization process automatically stringifies all keys.

Define a worker to process jobs in the events queue:

defmodule MyApp.Business do
  use Oban.Worker, queue: :events

  @impl Oban.Worker
  def perform(%Oban.Job{args: %{"id" => id} = args}) do
    model = MyApp.Repo.get(MyApp.Business.Man, id)

    case args do
      %{"in_the" => "business"} ->
        IO.inspect(model)

      %{"vote_for" => vote} ->
        IO.inspect([vote, model])

      _ ->
        IO.inspect(model)
    end

    :ok
  end
end

The use macro also accepts options to customize max attempts, priority, tags, and uniqueness:

defmodule MyApp.LazyBusiness do
  use Oban.Worker,
    queue: :events,
    priority: 3,
    max_attempts: 3,
    tags: ["business"],
    unique: [period: 30]

  @impl Oban.Worker
  def perform(_job) do
    # do business slowly

    :ok
  end
end

Successful jobs should return :ok or an {:ok, value} tuple. The value returned from perform/1 is used to control whether the job is treated as a success, a failure, cancelled or deferred for retrying later.

See the Oban.Worker docs for more details on failure conditions and Oban.Telemetry for details on job reporting.

enqueueing-jobs

Enqueueing Jobs

Jobs are simply Ecto structs and are enqueued by inserting them into the database. For convenience and consistency all workers provide a new/2 function that converts an args map into a job changeset suitable for insertion:

%{id: 1, in_the: "business", of_doing: "business"}
|> MyApp.Business.new()
|> Oban.insert()

The worker's defaults may be overridden by passing options:

%{id: 1, vote_for: "none of the above"}
|> MyApp.Business.new(queue: :special, max_attempts: 5)
|> Oban.insert()

Jobs may be scheduled at a specific datetime in the future:

%{id: 1}
|> MyApp.Business.new(scheduled_at: ~U[2020-12-25 19:00:56.0Z])
|> Oban.insert()

Jobs may also be scheduled down to the second any time in the future:

%{id: 1}
|> MyApp.Business.new(schedule_in: 5)
|> Oban.insert()

Unique jobs can be configured in the worker, or when the job is built:

%{email: "brewster@example.com"}
|> MyApp.Mailer.new(unique: [period: 300, fields: [:queue, :worker])
|> Oban.insert()

Job priority can be specified using an integer from 0 to 3, with 0 being the default and highest priority:

%{id: 1}
|> MyApp.Backfiller.new(priority: 2)
|> Oban.insert()

Any number of tags can be added to a job dynamically, at the time it is inserted:

id = 1

%{id: id}
|> MyApp.OnboardMailer.new(tags: ["mailer", "record-#{id}"])
|> Oban.insert()

Multiple jobs can be inserted in a single transaction:

Ecto.Multi.new()
|> Oban.insert(:b_job, MyApp.Business.new(%{id: 1}))
|> Oban.insert(:m_job, MyApp.Mailer.new(%{email: "brewser@example.com"}))
|> Repo.transaction()

Occasionally you may need to insert a job for a worker that exists in another application. In that case you can use Oban.Job.new/2 to build the changeset manually:

%{id: 1, user_id: 2}
|> Oban.Job.new(queue: :default, worker: OtherApp.Worker)
|> Oban.insert()

Oban.insert/2,4 is the preferred way of inserting jobs as it provides some of Oban's advanced features (i.e., unique jobs). However, you can use your application's Repo.insert/2 function if necessary.

See Oban.Job.new/2 for a full list of job options.

configuring-queues

Configuring Queues

Queues are specified as a keyword list where the key is the name of the queue and the value is the maximum number of concurrent jobs. The following configuration would start four queues with concurrency ranging from 5 to 50:

queues: [default: 10, mailers: 20, events: 50, media: 5]

You may also use an expanded form to configure queues with individual overrides:

queues: [
  default: 10,
  events: [limit: 50, paused: true]
]

The events queue will now start in a paused state, which means it won't process anything until Oban.resume_queue/2 is called to start it.

There isn't a limit to the number of queues or how many jobs may execute concurrently in each queue. Some additional guidelines:

Caveats & Guidelines

  • Each queue will run as many jobs as possible concurrently, up to the configured limit. Make sure your system has enough resources (i.e. database connections) to handle the concurrent load.

  • Queue limits are local (per-node), not global (per-cluster). For example, running a queue with a local limit of one on three separate nodes is effectively a global limit of three. If you require a global limit you must restrict the number of nodes running a particular queue.

  • Only jobs in the configured queues will execute. Jobs in any other queue will stay in the database untouched.

  • Be careful how many concurrent jobs make expensive system calls (i.e. FFMpeg, ImageMagick). The BEAM ensures that the system stays responsive under load, but those guarantees don't apply when using ports or shelling out commands.

pruning-historic-jobs

Pruning Historic Jobs

Job stats and queue introspection are built on keeping job rows in the database after they have completed. This allows administrators to review completed jobs and build informative aggregates, at the expense of storage and an unbounded table size. To prevent the oban_jobs table from growing indefinitely, Oban provides active pruning of completed, cancelled and discarded jobs.

By default, the Pruner plugin retains jobs for 60 seconds. You can configure a longer retention period by providing a max_age in seconds to the Pruner plugin.

# Set the max_age for 5 minutes
config :my_app, Oban,
  plugins: [{Oban.Plugins.Pruner, max_age: 300}]
  ...

Caveats & Guidelines

  • Pruning is best-effort and performed out-of-band. This means that all limits are soft; jobs beyond a specified age may not be pruned immediately after jobs complete.

  • Pruning is only applied to jobs that are completed, cancelled or discarded. It'll never delete a new job, a scheduled job or a job that failed and will be retried.

unique-jobs

Unique Jobs

The unique jobs feature lets you specify constraints to prevent enqueueing duplicate jobs. Uniqueness is based on a combination of args, queue, worker, state and insertion time. It is configured at the worker or job level using the following options:

  • :period — The number of seconds until a job is no longer considered duplicate. You should always specify a period, otherwise Oban will default to 60 seconds. :infinity can be used to indicate the job be considered a duplicate as long as jobs are retained.

  • :fields — The fields to compare when evaluating uniqueness. The available fields are :args, :queue and :worker, by default all three are used.

  • :keys — A specific subset of the :args to consider when comparing against historic jobs. This allows a job with multiple key/value pairs in the args to be compared using only a subset of them.

  • :states — The job states that are checked for duplicates. The available states are :available, :scheduled, :executing, :retryable, :completed, :cancelled and :discarded. By default all states except for :discarded and :cancelled are checked, which prevents duplicates even if the previous job has been completed.

For example, configure a worker to be unique across all fields and states for 60 seconds:

use Oban.Worker, unique: [period: 60]

Configure the worker to be unique only by :worker and :queue:

use Oban.Worker, unique: [fields: [:queue, :worker], period: 60]

Or, configure a worker to be unique until it has executed:

use Oban.Worker, unique: [period: 300, states: [:available, :scheduled, :executing]]

Only consider the :url key rather than the entire args:

use Oban.Worker, unique: [fields: [:args, :worker], keys: [:url]]

You can use Oban.Job.states/0 to specify uniqueness across all states, including :discarded:

use Oban.Worker, unique: [period: 300, states: Oban.Job.states()]

Detecting Unique Conflicts

When unique settings match an existing job, the return value of Oban.insert/2 is still {:ok, job}. However, you can detect a unique conflict by checking the jobs' :conflict? field. If there was an existing job, the field is true; otherwise it is false.

You can use the :conflict? field to customize responses after insert:

with {:ok, %Job{conflict?: true}} <- Oban.insert(changeset) do
  {:error, :job_already_exists}
end

Note that conflicts are only detected for jobs enqueued through Oban.insert/2,3. Jobs enqueued through Oban.insert_all/2 do not use per-job unique configuration.

Replacing Values

In addition to detecting unique conflicts, passing options to replace can update any job field when there is a conflict. Any of the following fields can be replaced: args, max_attempts, meta, priority, queue, scheduled_at, tags, worker.

For example, to change the priority and increase max_attempts when there is a conflict:

BusinessWorker.new(
  args,
  max_attempts: 5,
  priority: 0,
  replace: [:max_attempts, :priority]
)

Another example is bumping the scheduled time on conflict. Either scheduled_at or schedule_in values will work, but the replace option is always scheduled_at.

UrgentWorker.new(args, schedule_in: 1, replace: [:scheduled_at])

Strong Guarantees

Unique jobs are guaranteed through transactional locks and database queries: they do not rely on unique constraints in the database. This makes uniqueness entirely configurable by application code, without the need for database migrations.

periodic-jobs

Periodic Jobs

Oban's Cron plugin registers workers a cron-like schedule and enqueues jobs automatically. Periodic jobs are declared as a list of {cron, worker} or {cron, worker, options} tuples:

config :my_app, Oban,
  repo: MyApp.Repo,
  plugins: [
    {Oban.Plugins.Cron,
     crontab: [
       {"* * * * *", MyApp.MinuteWorker},
       {"0 * * * *", MyApp.HourlyWorker, args: %{custom: "arg"}},
       {"0 0 * * *", MyApp.DailyWorker, max_attempts: 1},
       {"0 12 * * MON", MyApp.MondayWorker, queue: :scheduled, tags: ["mondays"]},
       {"@daily", MyApp.AnotherDailyWorker}
     ]}
  ]

The crontab would insert jobs as follows:

  • MyApp.MinuteWorker — Inserted once every minute
  • MyApp.HourlyWorker — Inserted at the first minute of every hour with custom args
  • MyApp.DailyWorker — Inserted at midnight every day with no retries
  • MyApp.MondayWorker — Inserted at noon every Monday in the "scheduled" queue
  • MyApp.AnotherDailyWorker — Inserted at midnight every day with no retries

The crontab format respects all standard rules and has one minute resolution. Jobs are considered unique for most of each minute, which prevents duplicate jobs with multiple nodes and across node restarts.

Like other jobs, recurring jobs will use the :queue specified by the worker module (or :default if one is not specified).

Cron Expressions

Standard Cron expressions are composed of rules specifying the minutes, hours, days, months and weekdays. Rules for each field are comprised of literal values, wildcards, step values or ranges:

  • * — Wildcard, matches any value (0, 1, 2, ...)
  • 0 — Literal, matches only itself (only 0)
  • */15 — Step, matches any value that is a multiple (0, 15, 30, 45)
  • 0-5 — Range, matches any value within the range (0, 1, 2, 3, 4, 5)
  • 0-9/2 - Step values can be used in conjunction with ranges (0, 2, 4, 6, 8)

Each part may have multiple rules, where rules are separated by a comma. The allowed values for each field are as follows:

  • minute — 0-59
  • hour — 0-23
  • days — 1-31
  • month — 1-12 (or aliases, JAN, FEB, MAR, etc.)
  • weekdays — 0-6 (or aliases, SUN, MON, TUE, etc.)

The following Cron extensions are supported:

  • @hourly0 * * * *
  • @daily (as well as @midnight) — 0 0 * * *
  • @weekly0 0 * * 0
  • @monthly0 0 1 * *
  • @yearly (as well as @annually) — 0 0 1 1 *
  • @reboot — Run once at boot across the entire cluster

Some specific examples that demonstrate the full range of expressions:

  • 0 * * * * — The first minute of every hour
  • */15 9-17 * * * — Every fifteen minutes during standard business hours
  • 0 0 * DEC * — Once a day at midnight during December
  • 0 7-9,4-6 13 * FRI — Once an hour during both rush hours on Friday the 13th

For more in depth information see the man documentation for cron and crontab in your system. Alternatively you can experiment with various expressions online at Crontab Guru.

Caveats & Guidelines

  • All schedules are evaluated as UTC unless a different timezone is provided. See Oban.Plugins.Cron for information about configuring a timezone.

  • Workers can be used for regular and scheduled jobs so long as they accept different arguments.

  • Duplicate jobs are prevented through transactional locks and unique constraints. Workers that are used for regular and scheduled jobs must not specify unique options less than 60s.

  • Long running jobs may execute simultaneously if the scheduling interval is shorter than it takes to execute the job. You can prevent overlap by passing custom unique opts in the crontab config:

    custom_args = %{scheduled: true}
    
    unique_opts = [
      period: 60 * 60 * 24,
      states: [:available, :scheduled, :executing]
    ]
    
    config :my_app, Oban,
      repo: MyApp.Repo,
      plugins: [
        {Oban.Plugins.Cron,
         crontab: [
           {"* * * * *", MyApp.SlowWorker, args: custom_args, unique: unique_opts}
         ]}
      ]

prioritizing-jobs

Prioritizing Jobs

Normally, all available jobs within a queue are executed in the order they were scheduled. You can override the normal behavior and prioritize or de-prioritize a job by assigning a numerical priority.

  • Priorities from 0-3 are allowed, where 0 is the highest priority and 3 is the lowest.

  • The default priority is 0, unless specified all jobs have an equally high priority.

  • All jobs with a higher priority will execute before any jobs with a lower priority. Within a particular priority jobs are executed in their scheduled order.

umbrella-apps

Umbrella Apps

If you need to run Oban from an umbrella application where more than one of the child apps need to interact with Oban, you may need to set the :name for each child application that configures Oban.

For example, your umbrella contains two apps: MyAppA and MyAppB. MyAppA is responsible for inserting jobs, while only MyAppB actually runs any queues.

Configure Oban with a custom name for MyAppA:

config :my_app_a, Oban,
  name: MyAppA.Oban,
  repo: MyApp.Repo

Then configure Oban for MyAppB with a different name:

config :my_app_b, Oban,
  name: MyAppB.Oban,
  repo: MyApp.Repo,
  queues: [default: 10]

Now, use the configured name when calling functions like Oban.insert/2, Oban.insert_all/2, Oban.drain_queue/2, etc., to reference the correct Oban process for the current application.

Oban.insert(MyAppA.Oban, MyWorker.new(%{}))
Oban.insert_all(MyAppB.Oban, multi, :multiname, [MyWorker.new(%{})])
Oban.drain_queue(MyAppB.Oban, queue: :default)

testing

Testing

Find testing setup, helpers, and strategies in the testing guide.

error-handling

Error Handling

When a job returns an error value, raises an error, or exits during execution the details are recorded within the errors array on the job. When the number of execution attempts is below the configured max_attempts limit, the job will automatically be retried in the future.

The retry delay has an exponential backoff, meaning the job's second attempt will be after 16s, third after 31s, fourth after 1m 36s, etc.

See the Oban.Worker documentation on "Customizing Backoff" for alternative backoff strategies.

error-details

Error Details

Execution errors are stored as a formatted exception along with metadata about when the failure occurred and which attempt caused it. Each error is stored with the following keys:

  • at The UTC timestamp when the error occurred at
  • attempt The attempt number when the error occurred
  • error A formatted error message and stacktrace

See the Instrumentation docs for an example of integrating with external error reporting systems.

limiting-retries

Limiting Retries

By default, jobs are retried up to 20 times. The number of retries is controlled by the max_attempts value, which can be set at the Worker or Job level. For example, to instruct a worker to discard jobs after three failures:

use Oban.Worker, queue: :limited, max_attempts: 3

limiting-execution-time

Limiting Execution Time

By default, individual jobs may execute indefinitely. If this is undesirable you may define a timeout in milliseconds with the timeout/1 callback on your worker module.

For example, to limit a worker's execution time to 30 seconds:

def MyApp.Worker do
  use Oban.Worker

  @impl Oban.Worker
  def perform(_job) do
    something_that_may_take_a_long_time()

    :ok
  end

  @impl Oban.Worker
  def timeout(_job), do: :timer.seconds(30)
end

The timeout/1 function accepts an Oban.Job struct, so you can customize the timeout using any job attributes.

Define the timeout value through job args:

def timeout(%_{args: %{"timeout" => timeout}}), do: timeout

Define the timeout based on the number of attempts:

def timeout(%_{attempt: attempt}), do: attempt * :timer.seconds(5)

instrumentation-and-logging

Instrumentation and Logging

Oban provides integration with Telemetry, a dispatching library for metrics. It is easy to report Oban metrics to any backend by attaching to :oban events.

Here is an example of a sample unstructured log handler:

defmodule MyApp.ObanLogger do
  require Logger

  def handle_event([:oban, :job, :start], measure, meta, _) do
    Logger.warn("[Oban] :started #{meta.worker} at #{measure.system_time}")
  end

  def handle_event([:oban, :job, event], measure, meta, _) do
    Logger.warn("[Oban] #{event} #{meta.worker} ran in #{measure.duration}")
  end
end

Attach the handler to success and failure events in application.ex:

events = [[:oban, :job, :start], [:oban, :job, :stop], [:oban, :job, :exception]]

:telemetry.attach_many("oban-logger", events, &MyApp.ObanLogger.handle_event/4, [])

The Oban.Telemetry module provides a robust structured logger that handles all of Oban's telemetry events. As in the example above, attach it within your application.ex module:

:ok = Oban.Telemetry.attach_default_logger()

For more details on the default structured logger and information on event metadata see docs for the Oban.Telemetry module.

reporting-errors

Reporting Errors

Another great use of execution data is error reporting. Here is an example of integrating with Sentry to report job failures:

defmodule ErrorReporter do
  def handle_event([:oban, :job, :exception], measure, meta, _) do
    extra =
      meta.job
      |> Map.take([:id, :args, :meta, :queue, :worker])
      |> Map.merge(measure)

    Sentry.capture_exception(meta.reason, stacktrace: meta.stacktrace, extra: extra)
  end
end

:telemetry.attach(
  "oban-errors",
  [:oban, :job, :exception],
  &ErrorReporter.handle_event/4,
  []
)

You can use exception events to send error reports to Honeybadger, Rollbar, AppSignal or any other application monitoring platform.

isolation

Isolation

Oban supports namespacing through PostgreSQL schemas, also called "prefixes" in Ecto. With prefixes your jobs table can reside outside of your primary schema (usually public) and you can have multiple separate job tables.

To use a prefix you first have to specify it within your migration:

defmodule MyApp.Repo.Migrations.AddPrefixedObanJobsTable do
  use Ecto.Migration

  def up do
    Oban.Migrations.up(prefix: "private")
  end

  def down do
    Oban.Migrations.down(prefix: "private")
  end
end

The migration will create the "private" schema and all tables, functions and triggers within that schema. With the database migrated you'll then specify the prefix in your configuration:

config :my_app, Oban,
  prefix: "private",
  repo: MyApp.Repo,
  queues: [default: 10]

Now all jobs are inserted and executed using the private.oban_jobs table. Note that Oban.insert/2,4 will write jobs in the private.oban_jobs table, you'll need to specify a prefix manually if you insert jobs directly through a repo.

supervisor-isolation

Supervisor Isolation

Not only is the oban_jobs table isolated within the schema, but all notification events are also isolated. That means that insert/update events will only dispatch new jobs for their prefix. You can run multiple Oban instances with different prefixes on the same system and have them entirely isolated, provided you give each supervisor a distinct id.

Here we configure our application to start three Oban supervisors using the "public", "special" and "private" prefixes, respectively:

def start(_type, _args) do
  children = [
    Repo,
    Endpoint,
    {Oban, name: ObanA, repo: Repo},
    {Oban, name: ObanB, repo: Repo, prefix: "special"},
    {Oban, name: ObanC, repo: Repo, prefix: "private"}
  ]

  Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor)
end

dynamic-repositories

Dynamic Repositories

Oban supports Ecto dynamic repositories through the :get_dynamic_repo option. To make this work, you need to run a separate Oban instance per each dynamic repo instance. Most often it's worth bundling each Oban and repo instance under the same supervisor:

def start_repo_and_oban(instance_id) do
  children = [
    {MyDynamicRepo, name: nil, url: repo_url(instance_id)},
    {Oban, name: instance_id, get_dynamic_repo: fn -> repo_pid(instance_id) end}
  ]

  Supervisor.start_link(children, strategy: :one_for_one)
end

The function repo_pid/1 must return the pid of the repo for the given instance. You can use Registry to register the repo (for example in the repo's init/2 callback) and discover it.

If your application exclusively uses dynamic repositories and doesn't specify all credentials upfront, you must implement an init/1 callback in your Ecto Repo. Doing so provides the Postgres notifier with the correct credentials on init, allowing jobs to process as expected.

Link to this section Summary

Functions

Cancel many jobs based on a queryable and mark them as cancelled to prevent them from running. Any currently executing jobs are killed while the others are ignored.

Cancel an executing, available, scheduled or retryable job and mark it as cancelled to prevent it from running. If the job is currently executing it will be killed and otherwise it is ignored.

Check the current state of a queue producer.

Returns a specification to start this module under a supervisor.

Retrieve the Oban.Config struct for a named Oban supervision tree.

Synchronously execute all available jobs in a queue.

Similar to insert/3, but raises an Ecto.InvalidChangesetError if the job can't be inserted.

Insert a new job into the database for execution.

Put a job insert operation into an Ecto.Multi.

Insert multiple jobs into the database for execution.

Pause a running queue, preventing it from executing any new jobs. All running jobs will remain running until they are finished.

Resume executing jobs in a paused queue.

Retries all jobs that match on the given queryable. Please note that no matter the queryable constraints, it will never retry available, executing or scheduled jobs.

Sets a job as available, adding attempts if already maxed out. If the job is currently available, executing or scheduled it will be ignored. The job is scheduled for immediate execution.

Scale the concurrency for a queue.

Starts an Oban supervision tree linked to the current process.

Start a new supervised queue.

Shutdown a queue's supervision tree and stop running jobs for that queue.

Returns the pid of the root Oban process for the given name.

Link to this section Types

@type changeset_or_fun() :: Oban.Job.changeset() | Oban.Job.changeset_fun()
@type changeset_wrapper() :: %{
  :changesets => Oban.Job.changeset_list(),
  optional(atom()) => term()
}
Link to this type

changesets_or_wrapper()

View Source
@type changesets_or_wrapper() :: Oban.Job.changeset_list() | changeset_wrapper()
Link to this type

changesets_or_wrapper_or_fun()

View Source
@type changesets_or_wrapper_or_fun() ::
  changesets_or_wrapper() | Oban.Job.changeset_list_fun()
@type drain_option() ::
  {:queue, queue_name()}
  | {:with_limit, pos_integer()}
  | {:with_recursion, boolean()}
  | {:with_safety, boolean()}
  | {:with_scheduled, boolean() | DateTime.t()}
@type drain_result() :: %{
  cancelled: non_neg_integer(),
  discard: non_neg_integer(),
  failure: non_neg_integer(),
  snoozed: non_neg_integer(),
  success: non_neg_integer()
}
@type multi() :: Ecto.Multi.t()
@type multi_name() :: Ecto.Multi.name()
@type name() :: term()
@type option() ::
  {:dispatch_cooldown, pos_integer()}
  | {:engine, module()}
  | {:get_dynamic_repo, nil | (() -> pid() | atom())}
  | {:log, false | Logger.level()}
  | {:name, name()}
  | {:node, binary()}
  | {:notifier, module()}
  | {:peer, false | module()}
  | {:plugins, false | [module() | {module() | Keyword.t()}]}
  | {:prefix, binary()}
  | {:queues, false | [{queue_name(), pos_integer() | Keyword.t()}]}
  | {:repo, module()}
  | {:shutdown_grace_period, timeout()}
  | {:testing, :disabled | :inline | :manual}
@type queue_name() :: atom() | binary()
@type queue_option() ::
  {:queue, queue_name()} | {:limit, pos_integer()} | {:local_only, boolean()}
@type queue_state() :: %{
  :limit => pos_integer(),
  :node => binary(),
  :paused => boolean(),
  :queue => queue_name(),
  :running => [pos_integer()],
  :started_at => DateTime.t(),
  :updated_at => DateTime.t(),
  optional(atom()) => any()
}

Link to this section Functions

Link to this function

cancel_all_jobs(name \\ __MODULE__, queryable)

View Source (since 2.9.0)
@spec cancel_all_jobs(name(), queryable :: Ecto.Queryable.t()) ::
  {:ok, non_neg_integer()}

Cancel many jobs based on a queryable and mark them as cancelled to prevent them from running. Any currently executing jobs are killed while the others are ignored.

If executing jobs happen to fail before cancellation then the state is set to cancelled. However, any that complete successfully will remain completed.

Only jobs with the statuses executing, available, scheduled, or retryable can be cancelled.

example

Example

Cancel all jobs:

Oban.cancel_all_jobs(Oban.Job)
{:ok, 9}

Cancel all jobs for a specific worker:

Oban.Job
|> Ecto.Query.where(worker: "MyApp.MyWorker")
|> Oban.cancel_all_jobs()
{:ok, 2}
Link to this function

cancel_job(name \\ __MODULE__, job_id)

View Source (since 1.3.0)
@spec cancel_job(name(), job_id :: pos_integer()) :: :ok

Cancel an executing, available, scheduled or retryable job and mark it as cancelled to prevent it from running. If the job is currently executing it will be killed and otherwise it is ignored.

If an executing job happens to fail before it can be cancelled the state is set to cancelled. However, if it manages to complete successfully then the state will still be completed.

example

Example

Cancel a scheduled job with the id 1:

Oban.cancel_job(1)
:ok
Link to this function

check_queue(name \\ __MODULE__, opts)

View Source (since 2.2.0)
@spec check_queue(name(), opts :: [{:queue, queue_name()}]) :: queue_state()

Check the current state of a queue producer.

This allows you to introspect on a queue's health by retrieving key attributes of the producer's state; values such as the current limit, the running job ids, and when the producer was started.

options

Options

  • :queue - a string or atom specifying the queue to check, required

example

Example

Oban.check_queue(queue: :default)
%{
  limit: 10,
  node: "me@local",
  paused: false,
  queue: "default",
  running: [100, 102],
  started_at: ~D[2020-10-07 15:31:00],
  updated_at: ~D[2020-10-07 15:31:00]
}
@spec child_spec([option()]) :: Supervisor.child_spec()

Returns a specification to start this module under a supervisor.

See Supervisor.

Link to this function

config(name \\ __MODULE__)

View Source (since 0.2.0)
@spec config(name()) :: Oban.Config.t()

Retrieve the Oban.Config struct for a named Oban supervision tree.

example

Example

Retrieve the default Oban instance config:

%Oban.Config{} = Oban.config()

Retrieve the config for an instance started with a custom name:

%Oban.Config{} = Oban.config(MyCustomOban)
Link to this function

drain_queue(name \\ __MODULE__, opts)

View Source (since 0.4.0)
@spec drain_queue(name(), [drain_option()]) :: drain_result()

Synchronously execute all available jobs in a queue.

All execution happens within the current process and it is guaranteed not to raise an error or exit.

Draining a queue from within the current process is especially useful for testing. Jobs that are enqueued by a process when Ecto is in sandbox mode are only visible to that process. Calling drain_queue/2 allows you to control when the jobs are executed and to wait synchronously for all jobs to complete.

failures-retries

Failures & Retries

Draining a queue uses the same execution mechanism as regular job dispatch. That means that any job failures or crashes are captured and result in a retry. Retries are scheduled in the future with backoff and won't be retried immediately.

By default jobs are executed in safe mode, just as they are in production. Safe mode catches any errors or exits and records the formatted error in the job's errors array. That means exceptions and crashes are not bubbled up to the calling process.

If you expect jobs to fail, would like to track failures, or need to check for specific errors you can pass the with_safety: false flag. See the "Options" section below for more details.

scheduled-jobs

Scheduled Jobs

By default, drain_queue/2 will execute all currently available jobs. In order to execute scheduled jobs, you may pass the with_scheduled: true which will cause all scheduled jobs to be marked as available beforehand. To run jobs scheduled up to a specific point in time, pass a DateTime instead.

options

Options

  • :queue - a string or atom specifying the queue to drain, required

  • :with_limit — the maximum number of jobs to drain at once. When recursion is enabled this is how many jobs are processed per-iteration.

  • :with_recursion — whether to keep draining a queue repeatedly when jobs insert more jobs

  • :with_safety — whether to silently catch errors when draining, defaults to true. When false, raised exceptions or unhandled exits are reraised (unhandled exits are wrapped in Oban.CrashError).

  • :with_scheduled — whether to include any scheduled jobs when draining, default false. When true, drains all scheduled jobs. When a DateTime is provided, drains all jobs scheduled up to, and including, that point in time.

example

Example

Drain a queue with three available jobs, two of which succeed and one of which fails:

Oban.drain_queue(queue: :default)
%{failure: 1, snoozed: 0, success: 2}

Drain a queue including any scheduled jobs:

Oban.drain_queue(queue: :default, with_scheduled: true)
%{failure: 0, snoozed: 0, success: 1}

Drain a queue including jobs scheduled up to a minute:

Oban.drain_queue(queue: :default, with_scheduled: DateTime.add(DateTime.utc_now(), 60, :second))

Drain a queue and assert an error is raised:

assert_raise RuntimeError, fn -> Oban.drain_queue(queue: :risky, with_safety: false) end

Drain a queue repeatedly until there aren't any more jobs to run. This is particularly useful for testing jobs that enqueue other jobs:

Oban.drain_queue(queue: :default, with_recursion: true)
%{failure: 1, snoozed: 0, success: 2}

Drain only the top (by scheduled time and priority) five jobs off a queue:

Oban.drain_queue(queue: :default, with_limit: 5)
%{failure: 0, snoozed: 0, success: 1}

Drain a queue recursively, only one job at a time:

Oban.drain_queue(queue: :default, with_limit: 1, with_recursion: true)
%{failure: 0, snoozed: 0, success: 3}
Link to this function

insert!(name \\ __MODULE__, changeset, opts \\ [])

View Source (since 0.7.0)
@spec insert!(name(), Oban.Job.changeset(), opts :: Keyword.t()) :: Oban.Job.t()

Similar to insert/3, but raises an Ecto.InvalidChangesetError if the job can't be inserted.

example

Example

Insert a single job:

job = Oban.insert!(MyApp.Worker.new(%{id: 1}))

Insert a job using a custom timeout:

job = Oban.insert!(MyApp.Worker.new(%{id: 1}), timeout: 10_000)

Insert a job using an alternative instance name:

job = Oban.insert!(MyOban, MyApp.Worker.new(%{id: 1}))
Link to this function

insert(name \\ __MODULE__, changeset, opts \\ [])

View Source (since 0.7.0)
@spec insert(name(), Oban.Job.changeset(), Keyword.t()) ::
  {:ok, Oban.Job.t()} | {:error, Oban.Job.changeset() | term()}
@spec insert(multi(), multi_name(), changeset_or_fun()) :: multi()

Insert a new job into the database for execution.

This and the other insert variants are the recommended way to enqueue jobs because they support features like unique jobs.

See the section on "Unique Jobs" for more details.

example

Example

Insert a single job:

{:ok, job} = Oban.insert(MyApp.Worker.new(%{id: 1}))

Insert a job while ensuring that it is unique within the past 30 seconds:

{:ok, job} = Oban.insert(MyApp.Worker.new(%{id: 1}, unique: [period: 30]))

Insert a job using a custom timeout:

{:ok, job} = Oban.insert(MyApp.Worker.new(%{id: 1}), timeout: 10_000)

Insert a job using an alternative instance name:

{:ok, job} = Oban.insert(MyOban, MyApp.Worker.new(%{id: 1}))
Link to this function

insert(name, multi, multi_name, changeset, opts)

View Source (since 0.7.0)
@spec insert(name(), multi(), multi_name(), changeset_or_fun(), Keyword.t()) ::
  multi()

Put a job insert operation into an Ecto.Multi.

Like insert/2, this variant is recommended over Ecto.Multi.insert because it supports all of Oban's features, i.e. unique jobs.

See the section on "Unique Jobs" for more details.

example

Example

Ecto.Multi.new()
|> Oban.insert("job-1", MyApp.Worker.new(%{id: 1}))
|> Oban.insert("job-2", fn _ -> MyApp.Worker.new(%{id: 2}) end)
|> MyApp.Repo.transaction()
Link to this function

insert_all(name \\ __MODULE__, changesets, opts \\ [])

View Source (since 0.9.0)

Insert multiple jobs into the database for execution.

There are a few important differences between this function and Ecto.Repo.insert_all/3:

  1. This function always returns a list rather than a tuple of {count, records}
  2. This function accepts a list of changesets rather than a list of maps or keyword lists

🌟 Unique Jobs and Batching

Only the SmartEngine in Oban Pro supports bulk unique jobs and automatic batching. With the basic engine, you must use insert/3 for unique support.

options

Options

Accepts any of Ecto's "Shared Options" such as timeout and log.

example

Example

Insert 100 jobs with a single operation:

1..100
|> Enum.map(&MyApp.Worker.new(%{id: &1}))
|> Oban.insert_all()

Insert with a custom timeout:

1..100
|> Enum.map(&MyApp.Worker.new(%{id: &1}))
|> Oban.insert_all(timeout: 10_000)

Insert with an alternative instance name:

changesets = Enum.map(1..100, &MyApp.Worker.new(%{id: &1}))
jobs = Oban.insert_all(MyOban, changesets)
Link to this function

insert_all(name, multi, multi_name, changesets, opts)

View Source (since 0.9.0)
@spec insert_all(
  name(),
  multi(),
  multi_name(),
  changesets_or_wrapper_or_fun(),
  Keyword.t()
) :: multi()

Put an insert_all operation into an Ecto.Multi.

This function supports the same features and has the same caveats as insert_all/2.

example

Example

Insert job changesets within a multi:

changesets = Enum.map(0..100, &MyApp.Worker.new(%{id: &1}))

Ecto.Multi.new()
|> Oban.insert_all(:jobs, changesets)
|> MyApp.Repo.transaction()

Insert job changesets using a function:

Ecto.Multi.new()
|> Ecto.Multi.insert(:user, user_changeset)
|> Oban.insert_all(:jobs, fn %{user: user} ->
  email_job = EmailWorker.new(%{id: user.id})
  staff_job = StaffWorker.new(%{id: user.id})
  [email_job, staff_job]
end)
|> MyApp.Repo.transaction()
Link to this function

pause_queue(name \\ __MODULE__, opts)

View Source (since 0.2.0)
@spec pause_queue(name(), opts :: [queue_option()]) :: :ok

Pause a running queue, preventing it from executing any new jobs. All running jobs will remain running until they are finished.

When shutdown begins all queues are paused.

options

Options

  • :queue - a string or atom specifying the queue to pause, required
  • :local_only - whether the queue will be paused only on the local node, default: false

Note: by default, Oban does not verify that the given queue exists unless :local_only is set to true as even if the queue does not exist locally, it might be running on another node.

example

Example

Pause the default queue:

Oban.pause_queue(queue: :default)
:ok

Pause the default queue, but only on the local node:

Oban.pause_queue(queue: :default, local_only: true)
:ok
Link to this function

resume_queue(name \\ __MODULE__, opts)

View Source (since 0.2.0)
@spec resume_queue(name(), opts :: [queue_option()]) :: :ok

Resume executing jobs in a paused queue.

options

Options

  • :queue - a string or atom specifying the queue to resume, required
  • :local_only - whether the queue will be resumed only on the local node, default: false

Note: by default, Oban does not verify that the given queue exists unless :local_only is set to true as even if the queue does not exist locally, it might be running on another node.

example

Example

Resume a paused default queue:

Oban.resume_queue(queue: :default)
:ok

Resume the default queue, but only on the local node:

Oban.resume_queue(queue: :default, local_only: true)
:ok
Link to this function

retry_all_jobs(name \\ __MODULE__, queryable)

View Source (since 2.9.0)
@spec retry_all_jobs(name(), queryable :: Ecto.Queryable.t()) ::
  {:ok, non_neg_integer()}

Retries all jobs that match on the given queryable. Please note that no matter the queryable constraints, it will never retry available, executing or scheduled jobs.

If no queryable is given, Oban will retry all jobs in retryable states.

example

Example

Retries all retryable jobs

Oban.retry_all_jobs(Oban.Job)
{:ok, 9}

Retries all retryable jobs with priority 0

Oban.Job
|> Ecto.Query.where(priority: 0)
|> Oban.retry_all_jobs()
{:ok, 5}
Link to this function

retry_job(name \\ __MODULE__, job_id)

View Source (since 2.2.0)
@spec retry_job(name :: atom(), job_id :: pos_integer()) :: :ok

Sets a job as available, adding attempts if already maxed out. If the job is currently available, executing or scheduled it will be ignored. The job is scheduled for immediate execution.

example

Example

Retry a discarded job with the id 1:

Oban.retry_job(1)
:ok
Link to this function

scale_queue(name \\ __MODULE__, opts)

View Source (since 0.2.0)
@spec scale_queue(name(), opts :: [queue_option()]) :: :ok

Scale the concurrency for a queue.

options

Options

  • :queue - a string or atom specifying the queue to scale, required
  • :limit — the new concurrency limit, required
  • :local_only — whether the queue will be scaled only on the local node, default: false

In addition, all engine-specific queue options are passed along after validation.

Note: by default, Oban does not verify that the given queue exists unless :local_only is set to true as even if the queue does not exist locally, it might be running on another node.

example

Example

Scale a queue up, triggering immediate execution of queued jobs:

Oban.scale_queue(queue: :default, limit: 50)
:ok

Scale the queue back down, allowing executing jobs to finish:

Oban.scale_queue(queue: :default, limit: 5)
:ok

Scale the queue only on the local node:

Oban.scale_queue(queue: :default, limit: 10, local_only: true)
:ok
Link to this function

start_link(opts)

View Source (since 0.1.0)
@spec start_link([option()]) :: Supervisor.on_start()

Starts an Oban supervision tree linked to the current process.

options

Options

These options are required; without them the supervisor won't start

  • :repo — specifies the Ecto repo used to insert and retrieve jobs

primary-options

Primary Options

These options determine what the system does at a high level, i.e. which queues to run.

  • :log — either false to disable logging or a standard log level (:error, :warn, :info, :debug). This determines whether queries are logged or not; overriding the repo's configured log level. Defaults to false, where no queries are logged.

  • :name — used for supervisor registration, it must be unique across an entire VM instance. Defaults to Oban

  • :node — used to identify the node that the supervision tree is running in. If no value is provided it will use the node name in a distributed system, or the hostname in an isolated node. See "Node Name" below.

  • :notifier — used to relay messages between processes, nodes, and the Postgres database.

    There are two built-in notifiers: Oban.Notifiers.Postgres, which uses Postgres PubSub; and Oban.Notifiers.PG, which uses process groups with distributed erlang. Defaults to the Postgres notifier.

  • :peer — used to specify which peer module to use for cluster leadership.

    There are two built-in peers: Oban.Peers.Postgres, which uses table-based leadership through the oban_peers table; and Oban.Peers.Global, which uses global locks through distributed Erlang.

    Leadership can be disabled by setting peer: false, but note that centralized plugins like Cron won't run without leadership.

    Defaults to the Postgres peer.

  • :plugins — a list or modules or module/option tuples that are started as children of an Oban supervisor. Any supervisable module is a valid plugin, i.e. a GenServer or an Agent.

  • :prefix — the query prefix, or schema, to use for inserting and executing jobs. An oban_jobs table must exist within the prefix. See the "Prefix Support" section in the module documentation for more details.

  • :queues — a keyword list where the keys are queue names and the values are the concurrency setting or a keyword list of queue options. For example, setting queues to [default: 10, exports: 5] would start the queues default and exports with a combined concurrency level of 15. The concurrency setting specifies how many jobs each queue will run concurrently.

    Queues accept additional override options to customize their behavior, e.g. by setting paused or dispatch_cooldown for a specific queue.

  • :testing — a mode that controls how an instance is configured for testing. When set to :inline or :manual queues, peers, and plugins are automatically disabled. Defaults to :disabled, no test mode.

twiddly-options

Twiddly Options

Additional options used to tune system behaviour. These are primarily useful for testing or troubleshooting and don't usually need modification.

  • :dispatch_cooldown — the minimum number of milliseconds a producer will wait before fetching and running more jobs. A slight cooldown period prevents a producer from flooding with messages and thrashing the database. The cooldown period directly impacts a producer's throughput: jobs per second for a single queue is calculated by (1000 / cooldown) * limit. For example, with a 5ms cooldown and a queue limit of 25 a single queue can run 5,000 jobs/sec.

    The default is 5ms and the minimum is 1ms, which is likely faster than the database can return new jobs to run.

  • :shutdown_grace_period - the amount of time a queue will wait for executing jobs to complete before hard shutdown, specified in milliseconds. The default is 15_000, or 15 seconds.

example

Example

To start an Oban supervisor within an application's supervision tree:

def start(_type, _args) do
  children = [MyApp.Repo, {Oban, queues: [default: 50]}]

  Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor)
end

node-name

Node Name

When the node value hasn't been configured it is generated based on the environment:

  • In a distributed system the node name is used
  • In a Heroku environment the system environment's DYNO value is used
  • Otherwise, the system hostname is used
Link to this function

start_queue(name \\ __MODULE__, opts)

View Source (since 0.12.0)
@spec start_queue(name(), opts :: Keyword.t()) :: :ok

Start a new supervised queue.

By default this starts a new supervised queue across all nodes running Oban on the same database and prefix. You can pass the option local_only: true if you prefer to start the queue only on the local node.

options

Options

  • :queue - a string or atom specifying the queue to start, required
  • :local_only - whether the queue will be started only on the local node, default: false
  • :limit - set the concurrency limit, required
  • :paused — set whether the queue starts in the "paused" state, optional

In addition, all engine-specific queue options are passed along after validation.

example

Example

Start the :priority queue with a concurrency limit of 10 across the connected nodes.

Oban.start_queue(queue: :priority, limit: 10)
:ok

Start the :media queue with a concurrency limit of 5 only on the local node.

Oban.start_queue(queue: :media, limit: 5, local_only: true)
:ok

Start the :media queue in a paused state.

Oban.start_queue(queue: :media, limit: 5, paused: true)
:ok
Link to this function

stop_queue(name \\ __MODULE__, opts)

View Source (since 0.12.0)
@spec stop_queue(name(), opts :: [queue_option()]) :: :ok

Shutdown a queue's supervision tree and stop running jobs for that queue.

By default this action will occur across all the running nodes. Still, if you prefer to stop the queue's supervision tree and stop running jobs for that queue only on the local node, you can pass the option: local_only: true

The shutdown process pauses the queue first and allows current jobs to exit gracefully, provided they finish within the shutdown limit.

Note: by default, Oban does not verify that the given queue exists unless :local_only is set to true as even if the queue does not exist locally, it might be running on another node.

options

Options

  • :queue - a string or atom specifying the queue to stop, required
  • :local_only - whether the queue will be stopped only on the local node, default: false

example

Example

Oban.stop_queue(queue: :default)
:ok

Oban.stop_queue(queue: :media, local_only: true)
:ok
Link to this function

whereis(name)

View Source (since 2.2.0)
@spec whereis(name()) :: pid() | nil

Returns the pid of the root Oban process for the given name.

example

Example

Find the default instance:

Oban.whereis(Oban)

Find a dynamically named instance:

Oban.whereis({:oban, 1})