[CI] Run parallel tests in parallel

Apparently, parallel tests aren't in fact run in parallel in the CI, see core/dune-common!406 (comment 37534)

What needs to be done for this? Is this an issue in the CI images, or in the .gitlab-ci.yml of the individual repos?

mentioned in merge request core/dune-common!406 (merged)

mentioned in merge request core/dune-common!405 (merged)

@joe: Some parallel tests miss MPI_RANKS & TIMEOUT in CMakeLists.txt.

I probably should also increase DUNE_MAX_TEST_CORES to something higher than 2 (probably to 4 given we currently have 4 cores per build).

The opts files provided as part of the duneci/base:* images now pass -DDUNE_MAX_TEST_CORES=${DUNECI_PARALLEL} to cmake if DUNECI_PARALLEL is set. The CI runner here in Dresden has DUNECI_PARALLEL=4, so parallel tests with up to 4 processes (instead of up to 2 processes) should now be run.

I also opened core/dune-common!411 (merged) to add MPI_RANKS to a few more tests in dune-common.

closed

mentioned in issue core/dune-common#38