tests/usr.bin/renice: Prevent running them in parallel

[olivier]

Summary

Those tests are failing when executed in parallel.

Test Plan

Before:

echo "parallelism=8" >> /etc/kyua/kyua.conf
cd /usr/tests
kyua test usr.bin/renice
usr.bin/renice/renice_test:renice_abs_pid  ->  passed  [0.011s]
usr.bin/renice/renice_test:renice_abs_pgid  ->  passed  [0.012s]
usr.bin/renice/renice_test:renice_abs_user  ->  passed  [0.015s]
usr.bin/renice/renice_test:renice_rel_pgid  ->  passed  [0.015s]
usr.bin/renice/renice_test:renice_rel_pid  ->  passed  [0.015s]
usr.bin/renice/renice_test:renice_rel_user  ->  failed: 6 != 9 (6 != 9)  [0.017s]
usr.bin/renice/renice_test:renice_delim  ->  passed  [0.033s]

Results file id is usr_tests.20220926-153624-323416
Results saved to /root/.kyua/store/results.usr_tests.20220926-153624-323416.db

6/7 passed (1 failed)

After:

kyua test usr.bin/renice
usr.bin/renice/renice_test:renice_abs_pgid  ->  passed  [0.012s]
usr.bin/renice/renice_test:renice_abs_pid  ->  passed  [0.009s]
usr.bin/renice/renice_test:renice_abs_user  ->  passed  [0.015s]
usr.bin/renice/renice_test:renice_delim  ->  passed  [0.038s]
usr.bin/renice/renice_test:renice_rel_pgid  ->  passed  [0.014s]
usr.bin/renice/renice_test:renice_rel_pid  ->  passed  [0.016s]
usr.bin/renice/renice_test:renice_rel_user  ->  passed  [0.018s]

Results file id is usr_tests.20220926-153848-447640
Results saved to /root/.kyua/store/results.usr_tests.20220926-153848-447640.db

7/7 passed (0 failed)

[arichardson]

Are these tests fundamentally incompatible with parallel execution? If not I'd prefer if they could be fixed. Alternatively this could go in as a workaround as long as there is a PR to ensure this gets cleaned up eventually.

[arichardson]

I just skimmed over this tests and it seems like the only one that modifies global state are renice_abs_user and renice_rel_user since all others only apply to the PID. I think it should be sufficient to split those two out into a separate test and set exclusive on that one? This would allow running the remaining tests in parallel and thereby increase throughput.

Unless it's possible to set is_exclusive on a single test case rather than the whole test suite?

[asomers]

Sadly, I think there's no way to set that property for an individual test case. I think it's ok to set it for the entire program, since these tests run pretty fast anyway.

[des]

In D36720#834623, @arichardson wrote:

Are these tests fundamentally incompatible with parallel execution?

The ones with user in their name can't be run concurrently. The others should be fine.