Corrections in parallelization vignette

[ManonSimonot]

No description provided.

[astamm]

Thanks.

Also, benchmarking shows that the future mechanism works as expected but we also need to make sure that the parallel mechanism also works as expected.

On that note, the double parallelism mechanism is required for now because we want to use future but need parallel in optimParallel and rgenoud but it is tricky to set up correctly because when you do:

future::plan(multisession, workers = ncores)
cl <- parallel::makeCluster(ncores)
parallel::setDefaultCluster(cl)

you set up parallel sessions (at least in the case of future). Hence you probably need to declare half the number of cores you want to use to spread all of them between future and parallel. Worth investigating as well.

[astamm]

Also you need future::multisession in place of multisession unless you import library(future) at the beginning of the document/script.

[astamm]

Also, when you are done and ready for merge, please let me know if the branch can be deleted (to avoid keeping useless branches). Ideally, we should even fork the repo and send PR from a personal accounts.