[openstack-dev] [oslo][messaging] Further improvements and refactoring

Jay Pipes jaypipes at gmail.com
Thu Jun 26 20:22:09 UTC 2014

Hey Alexei, thanks for sharing your findings. Comments inline.

On 06/26/2014 10:08 AM, Alexei Kornienko wrote:
> Hello,
> Returning to performance issues of oslo.messaging.
> I've found 2 biggest issue in existing implementation of rabbit (kombu)
> driver:
> 1) For almost every message sent/received a new object of
> Consumer/Publisher class is created. And each object of this class tries
> to declare it's queue even if it's already declared.
> https://github.com/openstack/oslo.messaging/blob/master/oslo/messaging/_drivers/impl_rabbit.py#L159
> This causes a huge slowdown.

"Huge" is descriptive but not quantitative :) Do you have any numbers 
that pinpoint the amount of time that is being spent reconstructing and 
declaring the queues, say, compared to the time spent doing transmission?

> 2) with issue #1 is fixed (I've applied a small hack to fix it in my
> repo) the next big issue araise. For every rpc message received a reply
> is sent when processing is done (it seems that reply is sent even for
> "cast" calls which it really strange to me). Reply sent is using
> connection pool to "speed up" replies. Due to bad implementation of
> custom connection pool for every message sent underlying connection
> channel is closed and reopened:
> https://github.com/openstack/oslo.messaging/blob/master/oslo/messaging/_drivers/impl_rabbit.py#L689
> Cause of this major issues oslo.messaging performance is at least 10
> times slower than it could be.

This ten times number... is that an estimate or do you have hard numbers 
that show that? Just curious.

> My opinion is that there is no simple and elegant fix for this issues in
> current implementation of oslo.messaging (most because of bad
> architecture of the library and processing flow). My proposal is that we
> should start working on new major release of messaging library with
> architectural issues fixed. This will allow us to avoid mentioned issues
> and provide much more performance and flexibility for end users.
> Main goal that we should achieve is separate rpc code from messaging
> code this will allow us to implement both parts in much simpler and
> cleaner way and in the same time it would be much faster.

Perhaps actually a better starting point would be to create a 
benchmarking harness that will allow us to see some baseline throughput 
numbers that we can then compare to the iterative improvements you will 


> Please share your thoughts on this topic.
> Regards,
> Alexei Kornienko
> On 06/16/2014 02:47 PM, Gordon Sim wrote:
>> On 06/13/2014 02:06 PM, Ihar Hrachyshka wrote:
>>> On 10/06/14 15:40, Alexei Kornienko wrote:
>>>> On 06/10/2014 03:59 PM, Gordon Sim wrote:
>> >>>
>>>>> I think there could be a lot of work required to significantly
>>>>> improve that driver, and I wonder if that would be better spent
>>>>> on e.g. the AMQP 1.0 driver which I believe will perform much
>>>>> better and will offer more choice in deployment.
>> >>
>>>> I agree with you on this. However I'm not sure that we can do such
>>>> a decision. If we focus on amqp driver only we should mention it
>>>> explicitly and deprecate qpid driver completely. There is no point
>>>> in keeping driver that is not really functional.
>>> The driver is functional. It may be not that efficient as
>>> alternatives, but that's not a valid reason to deprecate it.
>> The question in my view is what the plan is for ongoing development.
>> Will the driver get better over time, or is it likely to remain as is
>> at best (or even deteriorate)?
>> Choice is good, but every choice adds to the maintenance burden, in
>> testing against regressions if nothing else.
>> I think an explicit decision about the future is beneficial, whatever
>> the decision may be.
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