bigquery.it.ITBigQueryTest: testConnectionClose failed

[flaky-bot]

Note: #3805 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

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commit: c180ecb
buildURL: Build Status, Sponge
status: failed

[flaky-bot]

Looks like this issue is flaky. 😟

I'm going to leave this open and stop commenting.

A human should fix and close this.

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When run at the same commit (c180ecb), this test passed in one build (Build Status, Sponge) and failed in another build (Build Status, Sponge).

[SivamuruganP]

I investigated this and found that the "flake" is likely caused by the background thread printing an unhandled InterruptedException stack trace to stderr during shutdown.

I verified locally that the row count is stable (no massive data leak). I have raised a PR to handle the interruption gracefully and eliminate the log noise/CI failures.