Comment (by Ian Hinder):

I think the best way to fix this would be to add the option to specify that the test requires a specific number of threads in test.ccl, as is done for the number of processes. So we would have nthreads as well as nprocs. The test system would then set CACTUS_NUM_THREADS and OMP_NUM_THREADS, and Carpet would find a consistent setup.

This solution is probably also the most work to implement.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2289/ct_multilevel-tests-abort-when-run-using