PoC for batching in PeriodicReader#7930
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## main #7930 +/- ##
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- Coverage 81.7% 81.5% -0.2%
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Files 304 305 +1
Lines 23283 23430 +147
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+ Hits 19032 19116 +84
- Misses 3864 3926 +62
- Partials 387 388 +1
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Mar 17, 2026
…ader (#4895) Fixes #4852 ## Prior Art The Trace SDK and Logging SDK both support a `maxExportBatchSize` parameter to limit the number of spans/logs exported in a batch. The collector's exporter helper and batch processor support a `send_batch_max_size` configuration option, which (by default) applies to the number spans, logs, or metric data points. In all cases, the configured timeout applies to a single request. ## Requirements * Apply a limit to the number of metric data points exported in a single OTLP batch. * Maintain existing ordering of metric data points. Batching must not result in metric data from a subsequent Collect to be exported prior to data from the earlier Collect call. * Apply the timeout to individual requests, not to multiple requests * The batch size must apply to a single exporter, and if multiple exporters are used, each must be able to have its own batch size. ## Non-goals * Introduce any parallelism into the metric export path * Limit by bytes, or anything else ## Proposal Add `maxExportBatchSize` to the periodic exporting MetricReader. The periodic exporting MetricReader splits the batch of metric data points received from Collect, if necessary, and then serially invokes `Export` on each split batch with the configured timeout. ## Alternatives considered ### maxExportBatchSize for all MetricReaders Instead of applying to only periodic readers, the batch size could apply to all readers. This alternative is not chosen because * Splitting batches is only required for push exporters. * It makes more sense to group the batching configuration with timeout configuration (which is on the periodic exporting MetricReader). ### maxExportBatchSize on OTLP exporters Instead of being on the periodic exporting MetricReader, we could add this configuration on the OTLP http and grpc exporters. This alternative is not chosen because: * The timeout should apply to individual batches, not to many, split batches in order to match behavior of other SDKs and the collector. This is only possible if batches are split _before_ the exporter, since the Periodic MetricReader applies the timeout. * It is more helpful to provide this functionality for all exporters, so it doesn't need to be re-implemented or copied. Prototypes: * Go: open-telemetry/opentelemetry-go#7930 * [x] Links to the prototypes (when adding or changing features) * [x] [`CHANGELOG.md`](https://github.com/open-telemetry/opentelemetry-specification/blob/main/CHANGELOG.md) file updated for non-trivial changes * [x] [Spec compliance matrix](https://github.com/open-telemetry/opentelemetry-specification/blob/main/spec-compliance-matrix/template.yaml) updated if necessary
dashpole
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Adds experimental support for maxExportBatchSize using the `OTEL_GO_X_METRIC_EXPORT_BATCH_SIZE=<size>` environment variable. Previous prototype: #7930 This preserves existing behavior for timeouts when batching is not used, but individually applies the timeout to export calls when batching is used.
pellared
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Apr 23, 2026
…try#8071) Adds experimental support for maxExportBatchSize using the `OTEL_GO_X_METRIC_EXPORT_BATCH_SIZE=<size>` environment variable. Previous prototype: open-telemetry#7930 This preserves existing behavior for timeouts when batching is not used, but individually applies the timeout to export calls when batching is used.
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Batching logic is based on the collector's batchprocessor: https://github.com/open-telemetry/opentelemetry-collector/blob/587b90b9ecc1db959ee9104d5bf993591f80ca43/processor/batchprocessor/splitmetrics.go
PoC for open-telemetry/opentelemetry-specification#4895
This PR adds
metric.WithMaxExportBatchSizetogo.opentelemetry.io/sdk/metric, and causes the SDK to split batches before passing them to the exporter.One potential issue is that I was hoping the export timeout could be applied individually to each batch, rather than to multiple serial export calls. But currently, we apply the timeout to collect + export. I've changed it to apply the timeout individually to collect, and to each export, but I'm curious how acceptable other maintainers think this kind of change would be. In practice, I suspect Collect() is not a notable source of latency or timeouts.
The spec for the timeout says:
It would strike me as a bit odd if we did split metrics into batches to have the timeout still applied to the entire collect + multiple exports based on the spec.