opentelemetry-sdk: drop NaN measurements at instrument level to prevent aggregation poisoning#5336
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here is a ss of the fix for the teams reference 
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hey sir, switched all isnan checks to math.isfinite to cover both NaN and Inf, and added inf test cases for each instrument type |
xrmx
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done, added the actual value to all 5 warning messages |
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Pull request overview
This pull request updates the OpenTelemetry Python SDK metrics instrument implementations to proactively drop non-finite numeric measurements (NaN, +/-Inf) at the instrument/callback layer, preventing permanent corruption (“poisoning”) of downstream aggregations.
Changes:
- Added
math.isfinite(...)guards to synchronous instrument methods (Counter.add,UpDownCounter.add,Histogram.record,Gauge.set) and to the shared async callback path (_Asynchronous.callback) to skip non-finite values with a warning. - Added unit tests covering
NaNandInfinputs for the affected instruments and async callbacks. - Added a changelog entry documenting the fix.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/instrument.py |
Drops non-finite values before they reach measurement consumption/aggregation for both sync instruments and async callbacks. |
opentelemetry-sdk/tests/metrics/test_instrument.py |
Adds regression tests ensuring non-finite measurements are ignored (and valid measurements still pass through). |
.changelog/5336.fixed |
Records the behavioral fix for release notes. |
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added integration tests in |
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@RudraDudhat2509 you can resolve comments if they are addressed. Thanks for contributing :) |
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Summary
NaNmeasurements passed to metric instruments (e.g.counter.add(float("nan"))) were silently folded into running aggregations, permanently poisoning the sum, all subsequent exports emittednanwith no recovery pathif amount < 0guard onCounterandHistogramis bypassed byNaNbecause all IEEE 754 comparisons againstNaNreturnFalsemath.isnan()check at the instrument level (same layer as the existing negative-value guard) for all sync instruments (Counter,UpDownCounter,Histogram,Gauge) and in the async callback path, matching the approach taken in the Java SDK (open-telemetry/opentelemetry-java#5846, fixed in PR #5859)Closes #5330
What was tested
test_add_nantoTestCounterandTestUpDownCountertest_record_nantoTestHistogramtest_set_nantoTestGaugetest_nan_callback_value_is_droppedtoTestObservableGauge(verifies NaN from async callbacks is skipped, valid measurements still pass through)python -m pytest opentelemetry-sdk/tests/metrics/test_instrument.py)counter.add(1) → add(NaN) → add(5)now yieldssum = 6, notnan