ci: Enable parallel test execution

[AbgarSim]

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Fixes #4041

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[gemini-code-assist]

Summary of Changes

Hello @AbgarSim, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly upgrades the project's testing capabilities by integrating JUnit 5 and enabling parallel test execution. The primary goal is to enhance developer productivity and accelerate feedback loops by allowing tests to run concurrently, thereby reducing the overall test suite execution time.

Highlights

• JUnit 5 Configuration: A new junit-platform.properties file has been added to configure JUnit 5 for the project.
• Parallel Test Execution: Parallel test execution has been enabled for JUnit 5, allowing tests to run concurrently.
• Fixed Parallelism Strategy: The parallel execution strategy is set to 'fixed' with a parallelism of 8 threads, optimizing test runtime.

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[gemini-code-assist]

Code Review

This pull request introduces parallel test execution for JUnit 5 by adding a junit-platform.properties file. This is a great step towards speeding up the build. My review includes two suggestions to improve the parallel execution configuration. First, I recommend changing the method execution mode to same_thread to prevent potential race conditions in tests that are not thread-safe. Second, I suggest using a dynamic parallelism strategy instead of a fixed one to better adapt to different execution environments. These changes should make the parallel test execution more robust and efficient.

[gemini-code-assist]

Setting junit.jupiter.execution.parallel.mode.default to concurrent will execute test methods within the same test class in parallel. This can introduce flakiness and hard-to-debug race conditions if tests share mutable state via instance fields. A safer default is same_thread, which executes methods within a class sequentially but still allows different test classes to run in parallel. Please ensure that tests are designed to be thread-safe at the method level before using concurrent mode.

junit.jupiter.execution.parallel.mode.default=same_thread

[AbgarSim]

So testing locally seems that this same_thread is not helping at all with the speed as opposed to concurrent, also running locally a couple of times I don't see any flake failures. Please advice if we can leave as is and change if there are actually flaky tests due to this @lqiu96

[lqiu96]

Hmm, I just tried this locally and I think it should be helping:

Without parallel:

[INFO] Reactor Summary for BigQuery Parent 2.57.2-SNAPSHOT:
[INFO]
[INFO] BigQuery Parent .................................... SUCCESS [  0.762 s]
[INFO] BigQuery ........................................... SUCCESS [02:29 min]
[INFO] Google Cloud BigQuery BOM .......................... SUCCESS [  0.003 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  02:31 min
[INFO] Finished at: 2026-01-12T17:22:00-05:00
[INFO] ------------------------------------------------------------------------

Parallel:

[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for BigQuery Parent 2.57.2-SNAPSHOT:
[INFO]
[INFO] BigQuery Parent .................................... SUCCESS [  0.695 s]
[INFO] BigQuery ........................................... SUCCESS [ 28.755 s]
[INFO] Google Cloud BigQuery BOM .......................... SUCCESS [  0.004 s]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  29.753 s
[INFO] Finished at: 2026-01-12T17:24:15-05:00
[INFO] ------------------------------------------------------------------------

I think there is quite a big speed up (especially for our GraalVM tests).

[lqiu96]

/gcbrun

[lqiu96]

@AbgarSim resolved some flaky tests in a separate PR. If you pull the latest changes, the tests should pass now

[AbgarSim]

@AbgarSim resolved some flaky tests in a separate PR. If you pull the latest changes, the tests should pass now

Rebased

[lqiu96]

/gcbrun

[lqiu96]

Seems like we have a flaky test and some quota issue:

JUnit Jupiter:ITRemoteUDFTest:testRoutineRemoteUDF()
    MethodSource [className = 'com.google.cloud.bigquery.it.ITRemoteUDFTest', methodName = 'testRoutineRemoteUDF', methodParameterTypes = '']
    => com.google.cloud.bigquery.BigQueryException: An internal error occurred and the request could not be completed. This is usually caused by a transient issue. Retrying the job with back-off as described in the BigQuery SLA should solve the problem: https://cloud.google.com/bigquery/sla. If the error continues to occur please contact support at https://cloud.google.com/support. Error: 4316996

I'll re-run this in a bit and look to try and disable this test