Some tests involving thread fail in parallel

[teytaud]

First this is so COOL because it makes Pytest parallelization easy on CircleCI :-)

We see in
facebookresearch/nevergrad#1441 that for some tests involving thread, the test crashes.
Maybe a good global fix would be to re-run failed test without parallelism, or to be able to flag tests (e.g. noparallelism in the name...), so that all problems due to impossible parallelism (and which will probably impact only a few % of the running time anyway) are solved at once.

Anyway thanks, this is fantastic!

[ryanwilsonperkin]

Hey @teytaud thanks for reporting this, can you try to narrow this down to a minimal reproduction? There isn't anything here that I'd expect would cause it to be breaking with threads, but there may be some issues in that codebase in how they detect available parallelism.