[ISSUE #10240] Add BatchSplittingMetricExporter to prevent OTLP gRPC export failures#10239
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lizhimins merged 4 commits intoapache:developfrom Apr 3, 2026
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When high-cardinality metrics (consumer_group x topic) produce OTLP export payloads exceeding the gRPC 32MB limit or SLS per-RPC processing limit, all metrics fail to export. This adds a MetricExporter decorator that: - Splits large batches of MetricData objects into smaller sub-batches - Splits single oversized MetricData objects by their internal data points into multiple smaller MetricData objects (supports all 7 MetricDataType) - Configurable via BrokerConfig.metricsExportBatchMaxDataPoints (default 1000) - Fast path with zero overhead when data points are within threshold - Logs failed batch details for debugging
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Houlong66
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New commit: Fix AIOOBE from concurrent callback modificationAdded commit What changed: Impact: Shallow copy only (object references), ~800KB overhead per export cycle for 100K data points. Negligible compared to the gRPC export itself. This fix works together with the original batch-splitting logic — the snapshot ensures marshaling safety, while batch-splitting ensures payload size compliance. |
The OTel SDK's NumberDataPointMarshaler.createRepeated allocates an array based on points.size() then iterates. If callback threads concurrently add data points between size() and iteration, an ArrayIndexOutOfBoundsException occurs. This adds a defensive snapshot of all data point collections at the start of export(), ensuring the delegate exporter always receives immutable point collections.
- testSnapshotCreatesNewMetricData: verify delegate receives snapshotted MetricData, not the original reference - testSnapshotFallsBackToOriginal: verify catch block falls back to original when snapshot fails (e.g., mock without type) - testSnapshotPointsAreIndependentCopy: verify the snapshotted points collection is a separate instance from the original
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RongtongJin
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What is the purpose of the change
Closes #10240
When high-cardinality metrics (e.g., consumer lag with consumer_group × topic combinations) are exported
via OTLP gRPC, the payload can exceed the gRPC 32MB message size limit or the backend's per-RPC processing
limit, causing all metrics to fail to export.
The OpenTelemetry Java SDK does not support automatic batch splitting for metrics export
(see opentelemetry-java#5394).
This PR adds a
MetricExporterdecorator that:MetricDataobjects into smaller sub-batches by data point countMetricDataobjects by their internal data points into multiplesmaller
MetricDataobjects (supports all 7MetricDataTypevariants)BrokerConfig.metricsExportBatchMaxDataPoints(default 1000)Brief changelog
BatchSplittingMetricExporterimplementingMetricExporteras a decoratorBrokerMetricsManagerto wrapOtlpGrpcMetricExportermetricsExportBatchMaxDataPointsconfig toBrokerConfig(default 1000, dynamically updatable)Verifying this change
This change added tests and can be verified as follows:
mvn test -pl broker -Dtest=BatchSplittingMetricExporterTest