test_in_tail: fix flaky throttling test by allowing one extra watcher tick - #5489
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kenhys merged 1 commit intoSep 7, 2026
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… tick
The `test "lines collected with throttling"` still fails intermittently
on CI, this time on the upper bound:
elapsed_seconds 3.329012749999947 is out of allowed range:
lower: 0.6799999999999999 [sec]
upper: 3.3200000000000003 [sec].
The throttling state is re-checked only when the tail watcher is
notified. Once the file has been fully written, retries depend mainly on
the 1s timer tick. Whether the tick that lands exactly rate_period after
the previous read start already satisfies `time_spent >= rate_period`
depends on sub-millisecond scheduling differences, so the next read can
start one tick later, i.e. rate_period + 1s after the previous one.
The existing jitter (1.32s) already contains one watcher interval, but
that allowance is shared with the read/observation latency: when the
extra tick and a slow batch coincide, only 0.32s is left for the
read-time skew and the 0.1s polling of the test thread, which is not
enough on a slow runner.
Add the watcher interval to the upper bound explicitly, so the upper
bound tolerates the same read/observation latency as the lower bound on
top of the extra tick. The per-cycle line-count assertion is kept, so a
regression that actually breaks throttling is still detected.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Signed-off-by: Shizuo Fujita <fujita@clear-code.com>
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…one extra watcher tick (#5489) (#5495) **Which issue(s) this PR fixes**: Backport #5489 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> Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com> Co-authored-by: Shizuo Fujita <fujita@clear-code.com> Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
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Which issue(s) this PR fixes:
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