Changelog for Oban Pro v0.12


Worker Hooks

Worker hooks are gauranteed to trigger after a job finishes executing. They're defined as callback functions on the worker, or in separate modules for reuse across workers.

Think of hooks as a convenient alternative to globally attached telemetry handlers, but with clearer scoping and much more safety. They are purely for side-effects such as cleanup, logging, broadcasting notifications, updating other records, error notifications, etc.

There are three mechanisms for defining and attaching hooks:

  1. Implicitly—hooks are defined directly on the worker and they only run for that worker
  2. Explicitly—hooks are listed when defining a worker and they run anywhere they are listed
  3. Globally—hooks are executed for all Pro workers (only Pro workers)

It's possible to combine each type of hook on a single worker. When multiple hooks are stacked they're executed in the order: implicit, explicit, and then global.

Here's a simple example of defining an inline hook on a worker to let us know when a job is discarded:

defmodule MyApp.HookWorker do
  use Oban.Pro.Worker

  @impl Oban.Pro.Worker
  def process(_job) do
    # ...

  @impl Oban.Pro.Worker
  def after_process(:discard, %Job{} = job) do
    IO.puts "Job processed with this job will never complete: #{}"

  def after_process(_state, _job), do: :ok

Look at the Worker Hooks section for a complete usage guide and examples. Note, as part of an ongoing documentation enhancement we've replaced the old guide with proper moduledocs.


Global Partitioning

Rate limits aren't the only SmartEngine-powered limiters that can be partitioned! Now, with partitioned global limiting, you can enforce concurrency limits by the worker, args, and sub-keys within a queue, across all nodes (without clustering).

Here's an example of partitioning an exporters queue by the worker to minimize resource contention:

queues: [
  exporters: [
    local_limit: 6,
    global_limit: [allowed: 3, partition: [fields: [:worker]]]

In this example where we're partitioning a scrapers queue by the service_id value so only one service will run across all nodes:

queues: [
  scrapers: [
    local_limit: 10,
    global_limit: [allowed: 1, partition: [fields: [:args], keys: [:service_id]]]

To achieve this style of global limiting before, you'd need one queue for every partition, which is challenging to manage and puts additional strain on the database.

Learn more in the revamped Partitioning section of the SmartEngine guide.


Unique Jobs and Batching for Insert All

A long-standing "gotcha" of bulk inserting jobs with insert_all was the lack of unique support. To apply uniqueness, you had to insert jobs individually within a transaction (which is as slow as it sounds and led to frequent timeouts). Now, unique support is baked into the SmartEngine's insert_all implementation and works without any configuration:

- Repo.transaction(fn ->
-  Enum.each(lots_of_unique_jobs, &Oban.insert/1)
- end)

+ Oban.insert_all(lots_of_unique_jobs)

There's also automatic batching for insert_all. No more manually chunking massive job inserts to avoid PostgreSQL's parameter limits, the engine handles it all for you and enforces uniqueness the whole time:

- Repo.transaction(fn ->
-   lots_of_jobs
-   |> Enum.chunk_every(500)
-   |> Enum.each(&Oban.insert_all/1)
- end)

+ Oban.insert_all(lots_of_jobs, batch_size: 500)

Automatic batching, combined with insert placeholders, optimized locks, and streamlined replace, means bulk inserts with the SmartEngine is faster and more efficient.

Explore a little more (and we do mean little, there isn't much more to it) in the SmartEngine's Unique Bulk Insert section.


v0.12.3 — 2022-08-09


Bug Fixes

  • [SmartEngine] Restore global functionality with Postgres v10

    Prior to PG 11 there wasn't support for jsonb to integers. Oban officially supports back to PG 10, and we can work around the limitation by casting to text first.

  • [SmartEngine] Apply uniqueness within batches of insert_all_jobs

    Previously, uniqueness was only applied between batches. That meant uniquness wasn't enforced when inserting duplicates within a small-ish (<500) list.

  • [SmartEngine] Switch rate window time to full unix timestamp

    Some queues don't have new jobs for days. When that happens a the current time may be later in the day than the previous time, which breaks rate limit estimation. This switches to full unix timestamps for rate limit windows to prevent this issue and retain window accuracy across days.

  • [Chunk] Support manually cancelling jobs

    Chunk has always supported discarding some or all jobs from a chunk. Now that discarding is deprecated, chunk also supports cancelling as an alternative.

  • [DynamicQueues] Accept global partition options

  • [Testing] Remove use of tap/2 to restore Elixir v1.11 compatibility

  • [Producer] Explicitly set timestamp fields for all schemas

    Some applications override Ecto's default timestamp field, which breaks all DynamicCron and DynamicQueues queries and triggers a crash loop.


v0.12.2 — 2022-07-26


Bug Fixes

  • [SmartEngine] Fix stalling in queues using global limits

    Tracking global counts was subject to a race condition between an in-memory copy of the producer and async job acking. That led to inconsistent counts that would stop the queue from processing jobs correctly.

  • [SmartEngine] Remove use of Map.reject for pre Elixir 1.13 compatibility

  • [SmartEngine] Ensure timestamps are set without database interraction

  • [Testing] Deduplicate jobs for run_workflow when given with_summary: false

    Workflow jobs don't run in a predictable order due to dependencies. That means the same job may execute two or more times, but even still, it should only be returned from run_jobs once.

  • [Testing] Include cancelled state in drain_jobs summary now that it's possible to have inline cancelled jobs.

  • [Worker] Fix the attach_hook spec to account for {:error, reason} return

  • [DynamicPruner] Forward log and prefix to delete_all call in Multi

    Batch operations in a Multi don't have shared options applied automatically.


v0.12.1 — 2022-07-22


Bug Fixes

  • [SmartEngine] Safely cancel jobs that haven't ever ran.

    When a job was cancelled without ever having ran, it would cause an ack'ing error within the engine.

  • [SmartEngine] Record reason from {:cancel, reason} in the job's errors.

    The cancel_job callback signature remained the same, so this slipped through the cracks when the functionalty was added to the BasicEngine.


v0.12.0 — 2022-07-21



  • [DynamicPruner] Add a before_delete option to operate on jobs before they're deleted, e.g. for logging, reporting, cold-storage, etc.

  • [Batch] Accept batch_callback_queue option to override where callback jobs are enqueued.


Bug Fixes

  • [Workflow] Safely handle deleted upstream dependencies. Workflow jobs with a missing dependency no longer crash, and their status can be controlled with the new ignore_deleted workflow option.

  • [Workflow] Verify that jobs implement the workflow behaviour as they are added to a workflow.

  • [DynamicQueues] Default the local_limit to global_limit to match the behaviour of standard queues.

  • [SmartEngine] Restore accepting refresh_interval to control down-time record refreshing. As a virtual field, it wasn't included in the list of allowed keys.

  • [SmartEngine] Use the new shutdown callback for safer pausing during queue shutdown. During tests, or other situations where a database connection was no longer available, pausing could raise an unexpected error.

  • [SmartEngine] Prevent running jobs that exceed rate limit when there are large gaps between insertion/execution.

For changes prior to v0.12 see the v0.11 docs.