Skip to main content

Generic event bus for asynchronous cross-process communication

Project description


Documentation Status

Documentation hosted by ReadTheDocs

DISCLAIMER: This is alpha state software. Expect bugs.

Lahja is a generic event bus implementation written in Python 3.6+ that enables lightweight inter-process communication, based on non-blocking asynchronous IO

What is this for?

Lahja is tailored around one primary use case: enabling multi process Python applications to communicate via events between processes using non-blocking APIs based on asyncio or trio.

Key facts:

  • non-blocking APIs using asynchronous IO (asyncio / trio)
  • lightweight with zero dependencies
  • simple to use
  • easy multicasting of events (one event, many independent receivers)
  • easy event routing (e.g route event X only to certain receivers)
  • multiple consuming APIs to adapt to different use cases and styles

Developer Setup

If you would like to hack on lahja, please check out the Snake Charmers Tactical Manual for information on how we do:

  • Testing
  • Pull Requests
  • Code Style
  • Documentation

Development Environment Setup

You can set up your dev environment with:

git clone
cd lahja
virtualenv -p python3 venv
. venv/bin/activate
pip install -e .[dev]

Testing Setup

During development, you might like to have tests run on every file save.

Show flake8 errors on file change:

# Test flake8
when-changed -v -s -r -1 lahja/ tests/ -c "clear; flake8 lahja tests && echo 'flake8 success' || echo 'error'"

Run multi-process tests in one command, but without color:

# in the project root:
pytest --numprocesses=4 --looponfail --maxfail=1
# the same thing, succinctly:
pytest -n 4 -f --maxfail=1

Run in one thread, with color and desktop notifications:

cd venv
ptw --onfail "notify-send -t 5000 'Test failure ⚠⚠⚠⚠⚠' 'python 3 test on lahja failed'" ../tests ../lahja

Release setup

For Debian-like systems:

apt install pandoc

To release a new version:

make release bump=$$VERSION_PART_TO_BUMP$$

How to bumpversion

The version format for this repo is {major}.{minor}.{patch} for stable, and {major}.{minor}.{patch}-{stage}.{devnum} for unstable (stage can be alpha or beta).

To issue the next version in line, specify which part to bump, like make release bump=minor or make release bump=devnum.

If you are in a beta version, make release bump=stage will switch to a stable.

To issue an unstable version when the current version is stable, specify the new version explicitly, like make release bump="--new-version 4.0.0-alpha.1 devnum"

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

lahja-0.17.0.tar.gz (33.3 kB view hashes)

Uploaded source

Built Distribution

lahja-0.17.0-py3-none-any.whl (40.2 kB view hashes)

Uploaded py3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page