Crash (SEGV) in Producer class

[joaoe]

Description

In my project I derived a new class from Producer to either implement a Mock producer for unit tests or a local Producer that just took snapshots of messages to a local cache.

The code looked like this

class MyProducer(Producer):
    def __init__(self, config):
        # Don't call super().__init__()
        self._config = config

MyProducer().flush()

and then everything crashed.

Looking at the code, the Producer class internally is represented by Handle which has a rk property. This is set to NULL until __init__ is called, but a lot of the Handle code lacks NULL checks.

How to reproduce

See code example above.

Checklist

Please provide the following information:

• confluent-kafka-python and librdkafka version (confluent_kafka.version() and confluent_kafka.libversion()): master
• Apache Kafka broker version:
• Client configuration: {...}
• Operating system:
• Provide client logs (with 'debug': '..' as necessary)
• Provide broker log excerpts
• Critical issue

[pranavrth]

Is there any specific reason that you don't want to call super.init()?

[joaoe]

Is there any specific reason that you don't want to call super.init()?

Hi.
Not really. I started with a mock Producer like

class MyProducer(Producer):
    def __init__(self, config):
           # ...

that crashed so I just changed to

class MyProducer:
    __class__ = Producer
    def __init__(self, config):
           # ...

Regardless I think we can both agree that the code should not crash with SEGV :) I submitted a PR with many NULL checks that should make everything more stable, also with the AdminClient class.

[MSeal]

Yes inheritance shouldn't SEGV and NULL checks should be in place. The PR touches a lot of places so needs a little more careful review, especially given no one reviewed it for 2 years. I'll mark as HIGH priority so we can get the PR cleaned up and merged or this issue closed if unforeseen issues are present therein.

[k-raina]

Thanks for raising this issue!
We have fixed this in PR #2122