[Avocado-devel] Running tests in parallel

[Zubair Lutfullah Kakakhel]

Hi,

Thank you for your comprehensive reply!

Comments inline.

On 11/22/2016 02:11 PM, Cleber Rosa wrote:
> On 11/22/2016 07:53 AM, Zubair Lutfullah Kakakhel wrote:
>> Hi,
>>
>
> Hi Zubair,
>
>> There are quite a few threads about this and a trello card
>> https://trello.com/c/xNeR2slj/255-support-running-tests-in-parallel
>>
>> And the discussion leads to a complex multi-host RFC.
>> https://www.redhat.com/archives/avocado-devel/2016-March/msg00025.html
>>
>> Our requirement is simpler.
>> All we wanted to do is run disjoint simple (c executables) tests in
>> parallel.
>>
>
> Sounds fair enough.
>
>> I was wondering if somebody has a WIP branch that has some level of
>> implementation for this?
>
> I'm not familiar with a WiP or PoC on this (yet).  If anyone has
> experimented with it, I'd happy to hear about it.
>
>> Or If somebody is familiar with the code base, I'd appreciate some
>> direction on how to implement this.
>>
>
> Avocado already runs every single test in a fresh new process.  This is,
> at least theoretically,  a good start.  Also, the test process is
> handled based on the standard Python multiprocessing module:
>
> https://github.com/avocado-framework/avocado/blob/master/avocado/core/runner.py#L363
>
> The first experimentation I'd do would be to attempt using the also
> Python standard multiprocessing.Pool:
>
> https://docs.python.org/2.7/library/multiprocessing.html#using-a-pool-of-workers

In this case, there would be a separate python thread for each test being run in parallel.
Each python thread would actually call the test executable using a sub-process?

That can be OK for Desktops but won't scale well for using avocado in memory
constrained Embedded devices.

Please correct me if I am reading this incorrectly.

Regards,
ZubairLK

>
> This would most certainly lead to changes in how Avocado currently
> serially waits for the test status:
>
> https://github.com/avocado-framework/avocado/blob/master/avocado/core/runner.py#L403
>
> Which ultimately is added to the (Job wide) results:
>
> https://github.com/avocado-framework/avocado/blob/master/avocado/core/runner.py#L455
>
> Since the results for many tests will now be acquired in unpredictable
> order, this will require changes to the ResultEvent based plugins (such
> as the UI).
>
>> Thanks
>>
>> Regards,
>> ZubairLK
>>
>
> I hope this is a good initial set of pointers.  If you feel adventurous
> and wants to start hacking on this, you're more then welcome.
>
> BTW: we've had quite a number of features that started as
> experiments/ideas/not-really-perfect-pull-requests from the community
> that Avocado "core team" members embraced and pushed all the way to
> completeness.
>