Backport(v1.19): test_in_tail: fix flaky throttling test by allowing one extra watcher tick (#5489) - #5495
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… tick (#5489) **Which issue(s) this PR fixes**: Fixes # **What this PR does / why we need it**: The `lines collected with throttling` test still fails intermittently after #5381 and #5418, this time on the upper bound: [Ruby 3.3 on macOS CI](https://github.com/fluent/fluentd/actions/runs/34003950778/job/101426224818) measured 3.329s against a 3.32s limit. ``` 4) Failure: test: lines collected with throttling(TailInputTest::throttling logs at in_tail level): elapsed_seconds 3.329012749999947 is out of allowed range: lower: 0.6799999999999999 [sec] upper: 3.3200000000000003 [sec]. ``` Once the file has been written, retries depend mainly on the 1s watcher timer. A tick near the 2s rate-period boundary can arrive slightly too early, delaying the next read until the following tick. Local tracing confirmed read-start intervals of both approximately 2s and 3s. The existing 1.32s allowance covers both timer scheduling and read/observation latency. When an extra tick consumes 1s, only 0.32s remains for other delays—slightly less than this CI run needed. This PR adds one watcher interval to the upper bound, increasing it from 3.32s to 4.32s. The lower bound and record-count assertions remain unchanged. **Docs Changes**: N/A **Release Note**: N/A Signed-off-by: Shizuo Fujita <fujita@clear-code.com> Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com> Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Watson1978
approved these changes
Sep 14, 2026
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Which issue(s) this PR fixes:
Backport #5489
Fixes #
What this PR does / why we need it:
The
lines collected with throttlingtest still fails intermittently after #5381 and #5418, this time on the upper bound: Ruby 3.3 on macOS CI measured 3.329s against a 3.32s limit.Once the file has been written, retries depend mainly on the 1s watcher timer. A tick near the 2s rate-period boundary can arrive slightly too early, delaying the next read until the following tick. Local tracing confirmed read-start intervals of both approximately 2s and 3s.
The existing 1.32s allowance covers both timer scheduling and read/observation latency. When an extra tick consumes 1s, only 0.32s remains for other delays—slightly less than this CI run needed.
This PR adds one watcher interval to the upper bound, increasing it from 3.32s to 4.32s. The lower bound and record-count assertions remain unchanged.
Docs Changes:
N/A
Release Note:
N/A