dramatiq-pg − Postgres Broker for Dramatiq

dramatiq is a simple task queue implementation for Python3. dramatiq-pg provides a Postgres-based implementation of a dramatiq broker.

The project is not feature complete yet.

Features

• Super simple deployment.
• Uses plain psycopg2. No ORM.
• Stores message payload as native JSONb.
• Stores all messages in a single table, in a dedicated schema.
• Uses LISTEN/NOTIFY to keep worker sync. No polling.
• Replay pending messages on worker startup.
• Requeues failed tasks.
• Reliable thanks to Postgres MVCC.
• Self-healing. Old messages are purge from time to time.

Note that dramatiq assumes tasks are idempotent. This broker makes the same assumptions for recovering after a crash.

Installation

• Install dramatiq-pg package from PyPI:

  $ pip install dramatiq-pg
  

• Apply dramatiq_pg/schema.sql file in your database:

  $ psql -f dramatiq_pg/schema.sql
  

• Before importing actors, define global broker with a connection pool:

  import dramatiq
  import dramatiq_pg
  import psycopg2.pool
  
  pool = psycopg2.pool.ThreadedConnectionPool(0, 4, conninfo)
  dramatiq.set_broker(dramatiq_pg.PostgresBroker(pool=pool))
  

Now declare/import actors and manage worker just like any dramatiq setup. An example script is available, tested on CI.

The CLI tool dramatiq-pg allows you to show stats on the queue and purge old messages. See --help for details.

Roadmap

• Result storage as JSONb.
• Delayed task.

Feel free to suggest feature through support channels.

Support

If you encounter a bug or miss a feature, please open an issue on GitLab with as much information as possible.

dramatiq_pg is available under the PostgreSQL licence.