parallelism of pytest tests

[themr0c]

Issue Type

• Bug report

To execute the tests, pytest-xdist is installed as a requirement, but pytest is invoked without the -n option which would permit to have some parallelism during tests.

See: https://pypi.org/project/pytest-xdist/

In pytest.ini, we could complete the addopts line with some option relevant to travis runner (to be determined).

[pytest]
addopts = -n3

This option has to be tested: maybe it could influence positively the duration of travis builds.

[themr0c]

Travis engines have 2 cores:

https://docs.travis-ci.com/user/reference/overview/#virtualization-environments

[webknjaz]

FTR xdist internally identifies Travis and know that it has two cores

[webknjaz]

Depends on: #1573
Fix PoC: webknjaz@87ccd81

[decentral1se]

Added #1573 (comment). Any further ideas on this? I'm wondering if we can use State to have all this naming issue resolved internally (some k:v where instance maps to the instance+uuid naming or so) and keep the end-user facing instance names.

[webknjaz]

Not sure, it'd be also weird: when users will run docker ps they'll see instance names with UUIDs...

[webknjaz]

@lwm after rethinking what you wrote I think that you're actually on the right track and using state would probably be beneficial.

[decentral1se]

Further data points: #1715 (comment).

[ssbarnea]

I doubt we are facing a pytest-xdist issue here, is mostly the lack of concurrency support in molecule which prevents us from running tests in parallel. I attempted to run functional ones and it mainly felt appart. Still, this does not mean that we shoud not sort this. It just means that it will take a lot of time to make required changes for allowing molecule to run multiple instances in parallel, under the same user on a single machine.

I do want to be able to run molecule in parallel on multiple roles and multiple scenarios and I already have repositories where this is desirable. At this moment we run sequentially but this increases the runtime considerably as the number of scenarios and roles increases.