> ## Documentation Index
> Fetch the complete documentation index at: https://trunk-4cab4936-mintlify-bab0b22b.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Merge Queue: New testing capacity metrics

> The Merge Queue Prometheus endpoint now exposes separate gauges for active CI testing slots and PRs currently in the testing phase, making batching-aware capacity tracking straightforward.

**Two new gauges on the Merge Queue Prometheus endpoint make it easy to track CI capacity separately from the number of PRs under test.**

Previously, testing activity was reported as a single number, which conflated CI slot usage with the number of PRs in flight when batching was on. The endpoint now exposes:

* **`mq_testing_slots_active`** — number of active CI slots currently in use. A batch counts as one slot, so this maps directly to CI concurrency.
* **`mq_prs_testing`** — number of PRs currently in the `TESTING` state. With batching enabled, this can exceed `mq_testing_slots_active` because several PRs share a slot.

Use `mq_testing_slots_active` for CI utilization alerts against your configured concurrency, and `mq_prs_testing` when you want to see how many PRs are being validated at once.

Both metrics carry the standard `repo`, `branch`, and `queue_type` labels and are available at `GET /v1/getMergeQueueMetrics` alongside the existing point-in-time gauges and 1-hour window metrics.

See [Merge Queue metrics](/merge-queue/administration/metrics) for the full metric reference and example PromQL queries.