add opt-in go.memory.gc.cycles metric

Author: dashpole

.chloggen/go-gc-cycles.yaml

@@ -0,0 +1,22 @@
+# Use this changelog template to create an entry for release notes.
+#
+# If your change doesn't affect end users you should instead start
+# your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the area of concern in the attributes-registry, (e.g. http, cloud, db)
+component: go
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add the opt-in go.memory.gc.cycles metric.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+# The values here must be integers.
+issues: [3353]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

docs/runtime/go-metrics.md

@@ -149,6 +149,25 @@ This metric is [recommended][MetricRecommended].
 <!-- END AUTOGENERATED TEXT -->
 <!-- endsemconv -->
 
+### Metric: `go.memory.gc.cycles`
+
+This metric is [opt-in][MetricOptIn].
+
+<!-- semconv metric.go.memory.gc.cycles -->
+<!-- NOTE: THIS TEXT IS AUTOGENERATED. DO NOT EDIT BY HAND. -->
+<!-- see templates/registry/markdown/snippet.md.j2 -->
+<!-- prettier-ignore-start -->
+
+| Name | Instrument Type | Unit (UCUM) | Description | Stability | Entity Associations |
+| -------- | --------------- | ----------- | -------------- | --------- | ------ |
+| `go.memory.gc.cycles` | Counter | `{gc_cycle}` | Number of completed GC cycles. [1] | ![Development](https://img.shields.io/badge/-development-blue) | |
+
+**[1]:** Computed from `/gc/cycles/total:gc-cycles`.
+
+<!-- prettier-ignore-end -->
+<!-- END AUTOGENERATED TEXT -->
+<!-- endsemconv -->
+
 ## Go goroutines
 
 **Description:** Go metrics captured under the namespace `go.goroutine.*`
@@ -244,3 +263,4 @@ This metric is [recommended][MetricRecommended].
 [DocumentStatus]: https://opentelemetry.io/docs/specs/otel/document-status
 [MetricRecommended]: /docs/general/metric-requirement-level.md#recommended
 [RuntimeMetrics]: https://pkg.go.dev/runtime/metrics
+[MetricOptIn]: /docs/general/metric-requirement-level.md#opt-in

model/go/metrics.yaml

@@ -68,6 +68,19 @@ groups:
     unit: "By"
     stability: development
 
+  - id: metric.go.memory.gc.cycles
+    type: metric
+    metric_name: go.memory.gc.cycles
+    annotations:
+      code_generation:
+        metric_value_type: int
+    brief: "Number of completed GC cycles."
+    note: >
+      Computed from `/gc/cycles/total:gc-cycles`.
+    instrument: counter
+    unit: "{gc_cycle}"
+    stability: development
+
   - id: metric.go.goroutine.count
     type: metric
     metric_name: go.goroutine.count