[Bug] Closing the client while create_producer()/subscribe() is pending returns an uninitialized object; producer_name() then segfaults #318

Note: AI was used to help write this text and the patch; I reproduced and verified the results.

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• I searched in the issues and found nothing similar.

Version

• pulsar-client 3.13.0 (latest on PyPI), bundling pulsar-client-cpp 4.2.0
• Python 3.12, Linux x86_64
• Also reproduced against main at e0cff2c, built from source against pulsar-client-cpp 4.2.0. main is now bd46d51 (fix: register exception translator as module-local #315, a one-line change to how the exception translator is registered); the missing mapping is unchanged. The fix's tests were re-run on bd46d51 (2026-11-08).

Minimal reproduce step

No broker is needed: the service URL points at a port where nothing listens, so the lookup keeps retrying until close() cancels it.

import threading, pulsar

client = pulsar.Client('pulsar://127.0.0.1:1', operation_timeout_seconds=30)
threading.Timer(1.0, client.close).start()

producer = client.create_producer('my-topic')   # expected: an exception
print(repr(producer.topic()), producer.is_connected())   # prints: '' False
producer.producer_name()                          # Segmentation fault (exit code 139)

The C++ log shows the cause:

ERROR ClientImpl:275 | Error Checking/Getting Partition Metadata while creating producer on persistent://public/default/my-topic -- ResultDisconnected

What did you expect to see?

create_producer() raises an exception, the way it raises pulsar.ConnectError or pulsar.Timeout for other failures.

What did you see instead?

create_producer() returns normally. The returned pulsar.Producer wraps a default-constructed native Producer with no implementation behind it:

• topic() returns '', is_connected() returns False
• close() raises ProducerNotInitialized
• producer_name() and last_sequence_id() dereference a null pointer and crash the interpreter (SIGSEGV)

subscribe(), create_reader() and get_topic_partitions() act the same way: they return an empty Consumer, an empty Reader and [].

Anything else?

Root cause: raiseException() in src/exceptions.cc has no CASE_RESULT for ResultDisconnected, which pulsar-client-cpp added in 3.2.0. The switch's default: branch is return;, so any result code without a case is treated as success, and waitForAsyncValue() returns the default-constructed value. Compared with the Result enum in pulsar-client-cpp 4.2.0, ResultDisconnected is the only public error code missing from the list; the only other result without a case is the internal ResultRetryable = -1.

In pulsar-client-cpp 4.2.0 a pending lookup completes with ResultDisconnected when the client is closed (RetryableOperation::cancel()); a dropped connection during the lookup is retried and ends as ResultTimeout, so in practice the trigger is close() racing a pending call.

The null-pointer crash itself comes from pulsar-client-cpp: Producer::getProducerName(), getLastSequenceId() and getSchemaVersion() call impl_->... with no null check, while getTopic(), close(), sendAsync(), flushAsync() and isConnected() have one, as do Consumer's getters. Fixing the binding stops the public API from handing out such an object; the missing guards could be fixed separately in pulsar-client-cpp.

Are you willing to submit a PR?

• I'm willing to submit a PR!