[rabbitmq-discuss] Pika and threads

Alex Grönholm alex.gronholm at nextday.fi
Tue Jul 19 11:44:22 BST 2011

19.07.2011 13:37, Marek Majkowski kirjoitti:
> Alex,
> 2011/7/17 Alex Grönholm<alex.gronholm at nextday.fi>:
>> I wanted to use Pika to implement an RPC server using RabbitMQ. I found that
>> this was however not possible because when I process the request in a
>> thread, I have no good way to thread safely send the results back.
> Isn't that the point of RPC? To stop the request process/thread until
> the response comes back.
That way the server could only process one request at a time. Obviously 
that is not good enough. My server uses 15 worker threads (possibly 
processes in the future) which need to send results back to the client 
once they are done processing the request. I solved this by using 
TornadoConnection, since Tornado's I/O loop does implement the required 
functionality (add_callback()) and uses a proper waking mechanism unlike 
SelectConnection's. That way, when a worker thread wants to send its 
results back to the client, it can interrupt the I/O loop which then 
proceeds to send the data.
>> The IOLoop lacks a mechanism for interrupting it directly. The best I could
>> figure was setting a timeout of 0, but it might take up to a second for this
>> to happen, considerably adding to the response latency.
>> Why isn't there just a dummy signalling socket that could be used for
>> interrupting the poll?
> In the tutorials I was using BlockingConnection:
>     http://www.rabbitmq.com/tutorials/tutorial-six-python.html
> Is that of any use to you?
The docs say that BlockingConnection is legacy stuff and should not be 
used. Is this no longer the case?
> Cheers,
>    Marek

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