From: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>
Date: Mon, 21 Nov 2022 21:41:54 +0000 (+0000)
Subject: runtime/metrics: add /gc/heap/live:bytes
X-Git-Tag: go1.21rc1~336
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=ef2bb813c82d5a96bb0993be83a34bfccb5f8c77;p=gostls13.git

runtime/metrics: add /gc/heap/live:bytes

For #56857

Change-Id: I0622af974783ab435e91b9fb3c1ba43f256ee4ac
Reviewed-on: https://go-review.googlesource.com/c/go/+/497315
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Felix Geisendörfer <felix.geisendoerfer@datadoghq.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
---

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 4a51ae573f..ad6348136e 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -248,6 +248,13 @@ func initMetrics() {
 				out.scalar = in.sysStats.heapGoal
 			},
 		},
+		"/gc/heap/live:bytes": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = gcController.heapMarked
+			},
+		},
 		"/gc/heap/objects:objects": {
 			deps: makeStatDepSet(heapStatsDep),
 			compute: func(in *statAggregate, out *metricValue) {
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index 2d5b0f2195..f5b1020271 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -245,6 +245,11 @@ var allDesc = []Description{
 		Description: "Heap size target for the end of the GC cycle.",
 		Kind:        KindUint64,
 	},
+	{
+		Name:        "/gc/heap/live:bytes",
+		Description: "Heap memory occupied by live objects that were marked by the previous GC.",
+		Kind:        KindUint64,
+	},
 	{
 		Name:        "/gc/heap/objects:objects",
 		Description: "Number of objects, live or unswept, occupying heap memory.",
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index 34d2c09de6..fe0d1f58e9 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -180,6 +180,10 @@ Below is the full list of supported metrics, ordered lexicographically.
 	/gc/heap/goal:bytes
 		Heap size target for the end of the GC cycle.
 
+	/gc/heap/live:bytes
+		Heap memory occupied by live objects that were marked by the
+		previous GC.
+
 	/gc/heap/objects:objects
 		Number of objects, live or unswept, occupying heap memory.
 
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index d981c8ee00..c1a991ead0 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -28,6 +28,9 @@ func prepareAllMetricsSamples() (map[string]metrics.Description, []metrics.Sampl
 }
 
 func TestReadMetrics(t *testing.T) {
+	// Run a GC cycle to get some of the stats to be non-zero.
+	runtime.GC()
+
 	// Tests whether readMetrics produces values aligning
 	// with ReadMemStats while the world is stopped.
 	var mstats runtime.MemStats
@@ -128,6 +131,13 @@ func TestReadMetrics(t *testing.T) {
 			mallocs = samples[i].Value.Uint64()
 		case "/gc/heap/frees:objects":
 			frees = samples[i].Value.Uint64()
+		case "/gc/heap/live:bytes":
+			if live := samples[i].Value.Uint64(); live > mstats.HeapAlloc {
+				t.Errorf("live bytes: %d > heap alloc: %d", live, mstats.HeapAlloc)
+			} else if live == 0 {
+				// Might happen if we don't call runtime.GC() above.
+				t.Error("live bytes is 0")
+			}
 		case "/gc/heap/objects:objects":
 			checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapObjects)
 		case "/gc/heap/goal:bytes":