[rabbitmq-discuss] Pika: Error when doing a stop_consuming() from a timeout callback

[Gavin M. Roy]

On Thursday, July 28, 2011 at 6:45 PM, Christian Haintz wrote:

> Hi,
> 
> I want to stop the consuming loop of a BlockingConnection after some 
> timeout. I used the following code. Producer is not running because I
> want to simulate the timeout. Current pika version is used from github.
I'd not consider the master branch on Pika stable, which is one of the reasons I've not tagged 0.9.6. I'd do a pip install of 0.9.5 and see if that solves your problem. 

Gavin

> 
> --------8<--------- snip ----------8<-----------
> import pika
> connection = pika.BlockingConnection(pika.ConnectionParameters(
>  host='localhost'))
> 
> channel = connection.channel()
> 
> result = channel.queue_declare(exclusive=True)
> callback_queue = result.method.queue
> 
> def on_response(self, ch, method, props, body):
>  #do some processing
>  channel.stop_consuming()
> 
> # normaly i do some publish here but that's not relevant
> # to reproduce the error
> 
> channel.basic_consume(on_response, no_ack=True,
>  queue=callback_queue)
> 
> def panic():
>  channel.stop_consuming()
> 
> connection.add_timeout(1, panic)
> channel.start_consuming()
> 
> --------8<------- snip end --------8<-----------
> 
> But I get the following error:
> 
> --------8<--------- snip ----------8<-----------
> $ python pika_test.py
> /Users/christian/devel/pika/pika/callback.py:69: UserWarning: 
> CallbackManager.add: Duplicate callback found for "1:Basic.CancelOk"
>  (self.__class__.__name__, prefix, key))
> Traceback (most recent call last):
>  File "pika_test.py", line 21, in <module>
>  channel.start_consuming()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 307, in start_consuming
>  self.transport.connection.process_data_events()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 104, in process_data_events
>  self.process_timeouts()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 164, in process_timeouts
>  self._timeouts[timeout_id]['handler']()
>  File "pika_test.py", line 18, in panic
>  channel.stop_consuming()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 318, in stop_consuming
>  self.basic_cancel(consumer_tag)
>  File "/Users/christian/devel/pika/pika/channel.py", line 333, in 
> basic_cancel
>  self._on_cancel_ok, [spec.Basic.CancelOk])
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 220, in rpc
>  self.send_method(method, None, wait)
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 249, in send_method
>  self.connection.process_data_events()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 104, in process_data_events
>  self.process_timeouts()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 164, in process_timeouts
>  self._timeouts[timeout_id]['handler']()
>  File "pika_test.py", line 18, in panic
>  channel.stop_consuming()
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 318, in stop_consuming
>  self.basic_cancel(consumer_tag)
>  File "/Users/christian/devel/pika/pika/channel.py", line 333, in 
> basic_cancel
>  self._on_cancel_ok, [spec.Basic.CancelOk])
>  File 
> "/Users/christian/devel/pika/pika/adapters/blocking_connection.py", line 
> 209, in rpc
>  self._on_rpc_complete)
> TypeError: 'NoneType' object is not iterable
> 
> 
> What I am doing wrong? Are the timeout callbacks not capable of stopping 
> the consumer?
> 
> 
> Regards,
> Christian
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