Limit the number of opened connections

By default, each worker using an AiopgConnector will open up to 10 parallel connections. You can control this value with the maxsize parameter (from aiopg.create_pool())(see Mind the size of your PostgreSQL pool)

Disabling the LISTEN/NOTIFY feature (see How does this all work ?) will use one less connection per worker:

app = procrastinate.App(worker_defaults={"listen_notify": False})
# or when launching a worker:
app.run_worker(listen_notify=False)

This works from the command line too:

procrastinate worker --no-listen-notify

Finally, setting the maxsize argument of the AiopgConnector to 1 will also disable the LISTEN/NOTIFY feature, but you will receive a warning.