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Ensure --dist=loadscope is used when running pytest in parallel

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The loadscope setting is required for parallel execution of our system
tests using pytest. The option ensure that all tests within a single
(module) scope will be assigned to the same worker.

This is neccessary because the worker sets up the nameservers for all
the tests within a module scope. If tests from the same module would be
assigned to different workers, then the setup could happen multiple
times, causing a race condition. This happens because each module uses
deterministic port numbers for the nameservers.

(cherry picked from commit 8f57bce7af)
This commit is contained in:
Tom Krizek
2023-03-28 16:52:49 +02:00
parent ac1e7eb40d
commit a388a689cf
4 changed files with 24 additions and 14 deletions
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17
bin/tests/system/README
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@@ -97,12 +97,7 @@ Issuing plain `pytest` command without any argument will execute all tests
sequenatially. To execute them in parallel, ensure you have pytest-xdist
installed and run:
pytest --dist loadscope -n <number-of-workers>
It is vital to provide the `--dist loadscope` option when running the tests in
parallel to ensure tests from a single module are executed from the same
thread. Otherwise, there's a risk of port contention and inefficient use of
resources.
pytest -n <number-of-workers>
Running the System Tests Using the Legacy Runner
@@ -754,11 +749,13 @@ collisions are likely to occur.
Pytest-xdist is used for executing pytest test cases in parallel using the `-n
N_WORKERS` option. By default, xdist will distribute any test case to any
worker, which would lead to the issue described above. Therefore, it is vital
to use the `--dist loadscope` option which ensures that test cases within the
same (module) scope will be handled by the same worker.
worker, which would lead to the issue described above. Therefore, conftest.py
enforces equivalent of `--dist loadscope` option which ensures that test cases
within the same (module) scope will be handled by the same worker. Parallelism
is automatically disabled when xdist.scheduler.loadscope library is not
available.
$ pytest -n auto --dist loadscope
$ pytest -n auto
Test selection
---