`execution_time` is different than `profile` for some (rare) jobs

By construction, execution_time is supposed to be equal to the profile name.

However, in some cases we observe that a job has an execution time higher than expected.

Step to reproduce

Enter the nix shell for integration tests and run the test test_dm_users.py

nix-shell -A test
pytest test/test_dm_users.py

The test fails because it compares the two columns profile and execution_time of the file _jobs.csv, and it finds a mismatch in line 625:

test/test_dm_users.py:19: 
E               AssertionError: Error in /home/mael/big_files/batmen/test-out/dm_user_delay-toy_pform_taurus_like-empty_workload/_jobs.csv, line 625. Fileds `execution_time` and `profile` should be equal.
E               assert 19250.0 == 23442.083333

test/test_users.py:63: AssertionError

One can open the output _jobs.csv and see the mismatch in line 625. All the other execution times are correct in this file.

Possible explanations

• two many jobs on the same machine, competing for resources (eg asking 16 cores on a 12-core machine)

TODO

• build a test that display this unexpected behavior