[openstack-dev] Python overhead for rootwrap

Jay Pipes jaypipes at gmail.com
Fri Jul 26 15:34:08 UTC 2013


On 07/25/2013 04:21 PM, Joe Gordon wrote:
> Hi All,
>
> We have recently hit some performance issues with nova-network.  It
> turns out the root cause of this was we do roughly 20 rootwrapped shell
> commands, many inside of global locks.
> (https://bugs.launchpad.net/oslo/+bug/1199433)
>
> It turns out starting python itself, has a fairly significant overhead
> when compared to the run time of many of the binary commands we execute.
>
> For example:
>
> $ time python -c "print 'test'"
> test
>
> real0m0.023s
> user0m0.016s
> sys0m0.004s
>
>
> $ time ip a
> <...>
>
> real0m0.003s
> user0m0.000s
> sys0m0.000s
>
>
> While we have removed the extra overhead of using entry points, we are
> now hitting the overhead of just shelling out to python.

Hey Joe,

Just ask a question of you personally, off list... I was curious about 
the above statement about entry points. Could you elaborate a bit there? 
I thought OpenStack had moved *to* using entry points with stevedore?

Did this change recently?

Best,
-jay




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