Component(s)

exporter/exporterhelper

Is your feature request related to a problem? Please describe.

When troubleshooting exporter performance bottlenecks, there is no way to observe how many export requests are concurrently in-flight per exporter. The existing metrics (otelcol_exporter_sent_*, otelcol_exporter_send_failed_*) are cumulative counters, and otelcol_exporter_queue_size only reflects the queue depth — not how many requests are actively being sent to the downstream backend.

This makes it difficult to determine whether a specific exporter is saturating its concurrent worker pool (e.g., all num_consumers slots are occupied) or if a slow backend is causing requests to pile up at the send layer. While it is technically possible to derive in-flight counts from trace data — by computing the overlap of active exporter/* spans — this requires additional trace storage, querying infrastructure, and non-trivial computation, making it impractical for real-time monitoring and alerting.

Describe the solution you'd like

Add a new metric otelcol_exporter_in_flight_requests as an Int64UpDownCounter (non-monotonic sum) that tracks the number of export requests currently being executed.

• Instrument: startOp() increments by +1, endOp() decrements by -1 in obsReportSender
• Unit: {request}
• Attributes: exporter (component ID), consistent with existing exporter metrics
• Stability: development

This metric would allow operators to:

• Detect when an exporter is at its concurrency limit (in_flight_requests == num_consumers)
• Identify slow backends causing request buildup
• Set alerts on sustained high in-flight counts before queue overflow occurs
• Compare in-flight levels across exporters to pinpoint bottlenecks

The implementation is minimal — it only touches obsReportSender.startOp()/endOp() in exporter/exporterhelper/internal/obs_report_sender.go.

Describe alternatives you've considered

No response

Additional context

No response

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