Producer.publish blocks forever on a closed connection when the transport_options of the connection does not specify a retry_policy

Kombu version = 4.4.0

When I call publish on a closed connection, it blocks forever; No exception, No error messages whatsoever. I tried to set a retry policy but The behaviour is the same.

Reproduce

from kombu import Connection

with Connection('pyamqp://localhost:8000') as conn:
    producer = conn.Producer(serializer='json')
    producer.publish(
        'Hello', errback=lambda: print('An error occured!'),
        retry=True, retry_policy={
            'interval_start': 0,
            'interval_step': 1,
            'interval_max': 5,
            'max_retries': 3,
        }
    )

    print('Published!')  # Never gets called

There’s no Rabbitmq server on localhost:8000 So I expect publish to raise a socket.timeout error when it’s unable to connect. Instead, it just hangs forever because it’s trying to establish a connection.

[danidee10]

@matteius I just opened a PR and I can confirm that the test fails in 4.4.0, 4.6.3 and 4.6.4 and it works in #1026

PR link: https://github.com/celery/kombu/pull/1093

[matteius]

@danidee10 In the original report you are testing this behavior outside of Celery correct? That is really cool and perhaps you wouldn’t mind submitting a PR with a unit test that shows this failure – we need more unit test coverage here regardless so if you can cover that regression with a failing test in your version of kombu 4.4.0 while in parallel test if the latest 4.6.3 and 4.6.4 (I am less likely to recommend 4.6.4, esp for folks using redis due to a different bug report, but try both) and also making a PR with such a unit test into celery/kombu will kick of the Travis Ci and Appveyor CI checks against master and so we can really pinpoint that it stays fixed and isn’t reintroduced as a regression later on.