From b08dfbaa439e4e396b979e02ea2e7d36972e8b7a Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Wed, 1 Jul 2020 16:02:42 +0000
Subject: runtime,runtime/metrics: add memory metrics

This change adds support for a variety of runtime memory metrics and
contains the base implementation of Read for the runtime/metrics
package, which lives in the runtime.

It also adds testing infrastructure for the metrics package, and a bunch
of format and documentation tests.

For #37112.

Change-Id: I16a2c4781eeeb2de0abcb045c15105f1210e2d8a
Reviewed-on: https://go-review.googlesource.com/c/go/+/247041
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Trust: Michael Knyszek <mknyszek@google.com>
---
 src/runtime/metrics.go | 367 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 367 insertions(+)
 create mode 100644 src/runtime/metrics.go

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
new file mode 100644
index 0000000000..44b5a29751
--- /dev/null
+++ b/src/runtime/metrics.go
@@ -0,0 +1,367 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+// Metrics implementation exported to runtime/metrics.
+
+import (
+	"unsafe"
+)
+
+var (
+	// metrics is a map of runtime/metrics keys to
+	// data used by the runtime to sample each metric's
+	// value.
+	metricsSema uint32 = 1
+	metricsInit bool
+	metrics     map[string]metricData
+)
+
+type metricData struct {
+	// deps is the set of runtime statistics that this metric
+	// depends on. Before compute is called, the statAggregate
+	// which will be passed must ensure() these dependencies.
+	deps statDepSet
+
+	// compute is a function that populates a metricValue
+	// given a populated statAggregate structure.
+	compute func(in *statAggregate, out *metricValue)
+}
+
+// initMetrics initializes the metrics map if it hasn't been yet.
+//
+// metricsSema must be held.
+func initMetrics() {
+	if metricsInit {
+		return
+	}
+	metrics = map[string]metricData{
+		"/memory/classes/heap/free:bytes": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(in.heapStats.committed - in.heapStats.inHeap -
+					in.heapStats.inStacks - in.heapStats.inWorkBufs -
+					in.heapStats.inPtrScalarBits)
+			},
+		},
+		"/memory/classes/heap/objects:bytes": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.heapStats.inObjects
+			},
+		},
+		"/memory/classes/heap/released:bytes": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(in.heapStats.released)
+			},
+		},
+		"/memory/classes/heap/stacks:bytes": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(in.heapStats.inStacks)
+			},
+		},
+		"/memory/classes/heap/unused:bytes": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(in.heapStats.inHeap) - in.heapStats.inObjects
+			},
+		},
+		"/memory/classes/metadata/mcache/free:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.mCacheSys - in.sysStats.mCacheInUse
+			},
+		},
+		"/memory/classes/metadata/mcache/inuse:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.mCacheInUse
+			},
+		},
+		"/memory/classes/metadata/mspan/free:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.mSpanSys - in.sysStats.mSpanInUse
+			},
+		},
+		"/memory/classes/metadata/mspan/inuse:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.mSpanInUse
+			},
+		},
+		"/memory/classes/metadata/other:bytes": {
+			deps: makeStatDepSet(heapStatsDep, sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(in.heapStats.inWorkBufs+in.heapStats.inPtrScalarBits) + in.sysStats.gcMiscSys
+			},
+		},
+		"/memory/classes/os-stacks:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.stacksSys
+			},
+		},
+		"/memory/classes/other:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.otherSys
+			},
+		},
+		"/memory/classes/profiling/buckets:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.buckHashSys
+			},
+		},
+		"/memory/classes/total:bytes": {
+			deps: makeStatDepSet(heapStatsDep, sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(in.heapStats.committed+in.heapStats.released) +
+					in.sysStats.stacksSys + in.sysStats.mSpanSys +
+					in.sysStats.mCacheSys + in.sysStats.buckHashSys +
+					in.sysStats.gcMiscSys + in.sysStats.otherSys
+			},
+		},
+	}
+	metricsInit = true
+}
+
+// statDep is a dependency on a group of statistics
+// that a metric might have.
+type statDep uint
+
+const (
+	heapStatsDep statDep = iota // corresponds to heapStatsAggregate
+	sysStatsDep                 // corresponds to sysStatsAggregate
+	numStatsDeps
+)
+
+// statDepSet represents a set of statDeps.
+//
+// Under the hood, it's a bitmap.
+type statDepSet [1]uint64
+
+// makeStatDepSet creates a new statDepSet from a list of statDeps.
+func makeStatDepSet(deps ...statDep) statDepSet {
+	var s statDepSet
+	for _, d := range deps {
+		s[d/64] |= 1 << (d % 64)
+	}
+	return s
+}
+
+// differennce returns set difference of s from b as a new set.
+func (s statDepSet) difference(b statDepSet) statDepSet {
+	var c statDepSet
+	for i := range s {
+		c[i] = s[i] &^ b[i]
+	}
+	return c
+}
+
+// union returns the union of the two sets as a new set.
+func (s statDepSet) union(b statDepSet) statDepSet {
+	var c statDepSet
+	for i := range s {
+		c[i] = s[i] | b[i]
+	}
+	return c
+}
+
+// empty returns true if there are no dependencies in the set.
+func (s *statDepSet) empty() bool {
+	for _, c := range s {
+		if c != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+// has returns true if the set contains a given statDep.
+func (s *statDepSet) has(d statDep) bool {
+	return s[d/64]&(1<<(d%64)) != 0
+}
+
+// heapStatsAggregate represents memory stats obtained from the
+// runtime. This set of stats is grouped together because they
+// depend on each other in some way to make sense of the runtime's
+// current heap memory use. They're also sharded across Ps, so it
+// makes sense to grab them all at once.
+type heapStatsAggregate struct {
+	heapStatsDelta
+
+	// inObjects is the bytes of memory occupied by objects,
+	// derived from other values in heapStats.
+	inObjects uint64
+}
+
+// compute populates the heapStatsAggregate with values from the runtime.
+func (a *heapStatsAggregate) compute() {
+	memstats.heapStats.read(&a.heapStatsDelta)
+
+	// Calculate derived stats.
+	a.inObjects = uint64(a.largeAlloc - a.largeFree)
+	for i := range a.smallAllocCount {
+		a.inObjects += uint64(a.smallAllocCount[i]-a.smallFreeCount[i]) * uint64(class_to_size[i])
+	}
+}
+
+// sysStatsAggregate represents system memory stats obtained
+// from the runtime. This set of stats is grouped together because
+// they're all relatively cheap to acquire and generally independent
+// of one another and other runtime memory stats. The fact that they
+// may be acquired at different times, especially with respect to
+// heapStatsAggregate, means there could be some skew, but because of
+// these stats are independent, there's no real consistency issue here.
+type sysStatsAggregate struct {
+	stacksSys   uint64
+	mSpanSys    uint64
+	mSpanInUse  uint64
+	mCacheSys   uint64
+	mCacheInUse uint64
+	buckHashSys uint64
+	gcMiscSys   uint64
+	otherSys    uint64
+}
+
+// compute populates the sysStatsAggregate with values from the runtime.
+func (a *sysStatsAggregate) compute() {
+	a.stacksSys = memstats.stacks_sys.load()
+	a.buckHashSys = memstats.buckhash_sys.load()
+	a.gcMiscSys = memstats.gcMiscSys.load()
+	a.otherSys = memstats.other_sys.load()
+
+	systemstack(func() {
+		lock(&mheap_.lock)
+		a.mSpanSys = memstats.mspan_sys.load()
+		a.mSpanInUse = uint64(mheap_.spanalloc.inuse)
+		a.mCacheSys = memstats.mcache_sys.load()
+		a.mCacheInUse = uint64(mheap_.cachealloc.inuse)
+		unlock(&mheap_.lock)
+	})
+}
+
+// statAggregate is the main driver of the metrics implementation.
+//
+// It contains multiple aggregates of runtime statistics, as well
+// as a set of these aggregates that it has populated. The aggergates
+// are populated lazily by its ensure method.
+type statAggregate struct {
+	ensured   statDepSet
+	heapStats heapStatsAggregate
+	sysStats  sysStatsAggregate
+}
+
+// ensure populates statistics aggregates determined by deps if they
+// haven't yet been populated.
+func (a *statAggregate) ensure(deps *statDepSet) {
+	missing := deps.difference(a.ensured)
+	if missing.empty() {
+		return
+	}
+	for i := statDep(0); i < numStatsDeps; i++ {
+		if !missing.has(i) {
+			continue
+		}
+		switch i {
+		case heapStatsDep:
+			a.heapStats.compute()
+		case sysStatsDep:
+			a.sysStats.compute()
+		}
+	}
+	a.ensured = a.ensured.union(missing)
+}
+
+// metricValidKind is a runtime copy of runtime/metrics.ValueKind and
+// must be kept structurally identical to that type.
+type metricKind int
+
+const (
+	// These values must be kept identical to their corresponding Kind* values
+	// in the runtime/metrics package.
+	metricKindBad metricKind = iota
+	metricKindUint64
+	metricKindFloat64
+	metricKindFloat64Histogram
+)
+
+// metricSample is a runtime copy of runtime/metrics.Sample and
+// must be kept structurally identical to that type.
+type metricSample struct {
+	name  string
+	value metricValue
+}
+
+// metricValue is a runtime copy of runtime/metrics.Sample and
+// must be kept structurally identical to that type.
+type metricValue struct {
+	kind    metricKind
+	scalar  uint64         // contains scalar values for scalar Kinds.
+	pointer unsafe.Pointer // contains non-scalar values.
+}
+
+// agg is used by readMetrics, and is protected by metricsSema.
+//
+// Managed as a global variable because its pointer will be
+// an argument to a dynamically-defined function, and we'd
+// like to avoid it escaping to the heap.
+var agg statAggregate
+
+// readMetrics is the implementation of runtime/metrics.Read.
+//
+//go:linkname readMetrics runtime/metrics.runtime_readMetrics
+func readMetrics(samplesp unsafe.Pointer, len int, cap int) {
+	// Construct a slice from the args.
+	sl := slice{samplesp, len, cap}
+	samples := *(*[]metricSample)(unsafe.Pointer(&sl))
+
+	// Acquire the metricsSema but with handoff. This operation
+	// is expensive enough that queueing up goroutines and handing
+	// off between them will be noticably better-behaved.
+	semacquire1(&metricsSema, true, 0, 0)
+
+	// Ensure the map is initialized.
+	initMetrics()
+
+	// Clear agg defensively.
+	agg = statAggregate{}
+
+	// Sample.
+	for i := range samples {
+		sample := &samples[i]
+		data, ok := metrics[sample.name]
+		if !ok {
+			sample.value.kind = metricKindBad
+			continue
+		}
+		// Ensure we have all the stats we need.
+		// agg is populated lazily.
+		agg.ensure(&data.deps)
+
+		// Compute the value based on the stats we have.
+		data.compute(&agg, &sample.value)
+	}
+
+	semrelease(&metricsSema)
+}
-- 
cgit v1.3


From 07c3f65d53df7bb9f84bdbd2ab64c0ae12337e3e Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Thu, 6 Aug 2020 15:44:27 +0000
Subject: runtime,runtime/metrics: add heap object count metric

For #37112.

Change-Id: Idd3dd5c84215ddd1ab05c2e76e848aa0a4d40fb0
Reviewed-on: https://go-review.googlesource.com/c/go/+/247043
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 src/runtime/metrics.go             | 18 ++++++++++++++++--
 src/runtime/metrics/description.go |  5 +++++
 src/runtime/metrics/doc.go         |  3 +++
 src/runtime/metrics_test.go        |  2 ++
 4 files changed, 26 insertions(+), 2 deletions(-)

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 44b5a29751..cf619cca4b 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -38,6 +38,13 @@ func initMetrics() {
 		return
 	}
 	metrics = map[string]metricData{
+		"/gc/heap/objects:objects": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.heapStats.numObjects
+			},
+		},
 		"/memory/classes/heap/free:bytes": {
 			deps: makeStatDepSet(heapStatsDep),
 			compute: func(in *statAggregate, out *metricValue) {
@@ -210,9 +217,13 @@ func (s *statDepSet) has(d statDep) bool {
 type heapStatsAggregate struct {
 	heapStatsDelta
 
+	// Derived from values in heapStatsDelta.
+
 	// inObjects is the bytes of memory occupied by objects,
-	// derived from other values in heapStats.
 	inObjects uint64
+
+	// numObjects is the number of live objects in the heap.
+	numObjects uint64
 }
 
 // compute populates the heapStatsAggregate with values from the runtime.
@@ -221,8 +232,11 @@ func (a *heapStatsAggregate) compute() {
 
 	// Calculate derived stats.
 	a.inObjects = uint64(a.largeAlloc - a.largeFree)
+	a.numObjects = uint64(a.largeAllocCount - a.largeFreeCount)
 	for i := range a.smallAllocCount {
-		a.inObjects += uint64(a.smallAllocCount[i]-a.smallFreeCount[i]) * uint64(class_to_size[i])
+		n := uint64(a.smallAllocCount[i] - a.smallFreeCount[i])
+		a.inObjects += n * uint64(class_to_size[i])
+		a.numObjects += n
 	}
 }
 
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index 2e7df7e09f..47013e1451 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -50,6 +50,11 @@ type Description struct {
 // The English language descriptions below must be kept in sync with the
 // descriptions of each metric in doc.go.
 var allDesc = []Description{
+	{
+		Name:        "/gc/heap/objects:objects",
+		Description: "Number of objects, live or unswept, occupying heap memory.",
+		Kind:        KindUint64,
+	},
 	{
 		Name:        "/memory/classes/heap/free:bytes",
 		Description: "Memory that is available for allocation, and may be returned to the underlying system.",
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index fb4e23a2b5..4ac44bb19c 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -44,6 +44,9 @@ the documentation of the Name field of the Description struct.
 
 Supported metrics
 
+	/gc/heap/objects:objects
+		Number of objects, live or unswept, occupying heap memory.
+
 	/memory/classes/heap/free:bytes
 		Memory that is available for allocation, and may be returned
 		to the underlying system.
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index d925b057b0..6c0be7dc0b 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -70,6 +70,8 @@ func TestReadMetrics(t *testing.T) {
 			checkUint64(t, name, samples[i].Value.Uint64(), mstats.BuckHashSys)
 		case "/memory/classes/total:bytes":
 			checkUint64(t, name, samples[i].Value.Uint64(), mstats.Sys)
+		case "/gc/heap/objects:objects":
+			checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapObjects)
 		}
 	}
 }
-- 
cgit v1.3


From a8b28ebc87854fb6f2ba99f415f046dc2ff63604 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Thu, 6 Aug 2020 16:47:58 +0000
Subject: runtime,runtime/metrics: add heap goal and GC cycle metrics

This change adds three new metrics: the heap goal, GC cycle count, and
forced GC count. These metrics are identical to their MemStats
counterparts.

For #37112.

Change-Id: I5a5e8dd550c0d646e5dcdbdf38274895e27cdd88
Reviewed-on: https://go-review.googlesource.com/c/go/+/247044
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 src/runtime/metrics.go             | 51 ++++++++++++++++++++++++++++++++------
 src/runtime/metrics/description.go | 23 +++++++++++++++++
 src/runtime/metrics/doc.go         | 12 +++++++++
 src/runtime/metrics_test.go        |  8 ++++++
 4 files changed, 86 insertions(+), 8 deletions(-)

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index cf619cca4b..6595a4342c 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -7,6 +7,7 @@ package runtime
 // Metrics implementation exported to runtime/metrics.
 
 import (
+	"runtime/internal/atomic"
 	"unsafe"
 )
 
@@ -38,6 +39,34 @@ func initMetrics() {
 		return
 	}
 	metrics = map[string]metricData{
+		"/gc/cycles/automatic:gc-cycles": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.gcCyclesDone - in.sysStats.gcCyclesForced
+			},
+		},
+		"/gc/cycles/forced:gc-cycles": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.gcCyclesForced
+			},
+		},
+		"/gc/cycles/total:gc-cycles": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.gcCyclesDone
+			},
+		},
+		"/gc/heap/goal:bytes": {
+			deps: makeStatDepSet(sysStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = in.sysStats.heapGoal
+			},
+		},
 		"/gc/heap/objects:objects": {
 			deps: makeStatDepSet(heapStatsDep),
 			compute: func(in *statAggregate, out *metricValue) {
@@ -248,14 +277,17 @@ func (a *heapStatsAggregate) compute() {
 // heapStatsAggregate, means there could be some skew, but because of
 // these stats are independent, there's no real consistency issue here.
 type sysStatsAggregate struct {
-	stacksSys   uint64
-	mSpanSys    uint64
-	mSpanInUse  uint64
-	mCacheSys   uint64
-	mCacheInUse uint64
-	buckHashSys uint64
-	gcMiscSys   uint64
-	otherSys    uint64
+	stacksSys      uint64
+	mSpanSys       uint64
+	mSpanInUse     uint64
+	mCacheSys      uint64
+	mCacheInUse    uint64
+	buckHashSys    uint64
+	gcMiscSys      uint64
+	otherSys       uint64
+	heapGoal       uint64
+	gcCyclesDone   uint64
+	gcCyclesForced uint64
 }
 
 // compute populates the sysStatsAggregate with values from the runtime.
@@ -264,6 +296,9 @@ func (a *sysStatsAggregate) compute() {
 	a.buckHashSys = memstats.buckhash_sys.load()
 	a.gcMiscSys = memstats.gcMiscSys.load()
 	a.otherSys = memstats.other_sys.load()
+	a.heapGoal = atomic.Load64(&memstats.next_gc)
+	a.gcCyclesDone = uint64(memstats.numgc)
+	a.gcCyclesForced = uint64(memstats.numforcedgc)
 
 	systemstack(func() {
 		lock(&mheap_.lock)
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index 47013e1451..66d229c270 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -50,6 +50,29 @@ type Description struct {
 // The English language descriptions below must be kept in sync with the
 // descriptions of each metric in doc.go.
 var allDesc = []Description{
+	{
+		Name:        "/gc/cycles/automatic:gc-cycles",
+		Description: "Count of completed GC cycles generated by the Go runtime.",
+		Kind:        KindUint64,
+		Cumulative:  true,
+	},
+	{
+		Name:        "/gc/cycles/forced:gc-cycles",
+		Description: "Count of completed forced GC cycles.",
+		Kind:        KindUint64,
+		Cumulative:  true,
+	},
+	{
+		Name:        "/gc/cycles/total:gc-cycles",
+		Description: "Count of all completed GC cycles.",
+		Kind:        KindUint64,
+		Cumulative:  true,
+	},
+	{
+		Name:        "/gc/heap/goal:bytes",
+		Description: "Heap size target for the end of the GC cycle.",
+		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 4ac44bb19c..9b44e73ee6 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -44,6 +44,18 @@ the documentation of the Name field of the Description struct.
 
 Supported metrics
 
+	/gc/cycles/automatic:gc-cycles
+		Count of completed GC cycles generated by the Go runtime.
+
+	/gc/cycles/forced:gc-cycles
+		Count of completed forced GC cycles.
+
+	/gc/cycles/total:gc-cycles
+		Count of all completed GC cycles.
+
+	/gc/heap/goal:bytes
+		Heap size target for the end of the GC cycle.
+
 	/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 6c0be7dc0b..3724760294 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -72,6 +72,14 @@ func TestReadMetrics(t *testing.T) {
 			checkUint64(t, name, samples[i].Value.Uint64(), mstats.Sys)
 		case "/gc/heap/objects:objects":
 			checkUint64(t, name, samples[i].Value.Uint64(), mstats.HeapObjects)
+		case "/gc/heap/goal:bytes":
+			checkUint64(t, name, samples[i].Value.Uint64(), mstats.NextGC)
+		case "/gc/cycles/automatic:gc-cycles":
+			checkUint64(t, name, samples[i].Value.Uint64(), uint64(mstats.NumGC-mstats.NumForcedGC))
+		case "/gc/cycles/forced:gc-cycles":
+			checkUint64(t, name, samples[i].Value.Uint64(), uint64(mstats.NumForcedGC))
+		case "/gc/cycles/total:gc-cycles":
+			checkUint64(t, name, samples[i].Value.Uint64(), uint64(mstats.NumGC))
 		}
 	}
 }
-- 
cgit v1.3


From 8e2370bf7f0c992ce1ea5dc54b43551cea71a485 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Thu, 6 Aug 2020 19:04:46 +0000
Subject: runtime,runtime/metrics: add object size distribution metrics

This change adds metrics for the distribution of objects allocated and
freed by size, mirroring MemStats' BySize field.

For #37112.

Change-Id: Ibaf1812da93598b37265ec97abc6669c1a5efcbf
Reviewed-on: https://go-review.googlesource.com/c/go/+/247045
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 src/runtime/metrics.go             | 52 ++++++++++++++++++++++++++++++++++++++
 src/runtime/metrics/description.go | 10 ++++++++
 src/runtime/metrics/doc.go         |  6 +++++
 src/runtime/metrics_test.go        | 36 ++++++++++++++++++++++++++
 4 files changed, 104 insertions(+)

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 6595a4342c..32d8ab461c 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -18,6 +18,8 @@ var (
 	metricsSema uint32 = 1
 	metricsInit bool
 	metrics     map[string]metricData
+
+	sizeClassBuckets []float64
 )
 
 type metricData struct {
@@ -38,6 +40,10 @@ func initMetrics() {
 	if metricsInit {
 		return
 	}
+	sizeClassBuckets = make([]float64, _NumSizeClasses)
+	for i := range sizeClassBuckets {
+		sizeClassBuckets[i] = float64(class_to_size[i])
+	}
 	metrics = map[string]metricData{
 		"/gc/cycles/automatic:gc-cycles": {
 			deps: makeStatDepSet(sysStatsDep),
@@ -60,6 +66,26 @@ func initMetrics() {
 				out.scalar = in.sysStats.gcCyclesDone
 			},
 		},
+		"/gc/heap/allocs-by-size:objects": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				hist := out.float64HistOrInit(sizeClassBuckets)
+				hist.counts[len(hist.counts)-1] = uint64(in.heapStats.largeAllocCount)
+				for i := range hist.buckets {
+					hist.counts[i] = uint64(in.heapStats.smallAllocCount[i])
+				}
+			},
+		},
+		"/gc/heap/frees-by-size:objects": {
+			deps: makeStatDepSet(heapStatsDep),
+			compute: func(in *statAggregate, out *metricValue) {
+				hist := out.float64HistOrInit(sizeClassBuckets)
+				hist.counts[len(hist.counts)-1] = uint64(in.heapStats.largeFreeCount)
+				for i := range hist.buckets {
+					hist.counts[i] = uint64(in.heapStats.smallFreeCount[i])
+				}
+			},
+		},
 		"/gc/heap/goal:bytes": {
 			deps: makeStatDepSet(sysStatsDep),
 			compute: func(in *statAggregate, out *metricValue) {
@@ -370,6 +396,32 @@ type metricValue struct {
 	pointer unsafe.Pointer // contains non-scalar values.
 }
 
+// float64HistOrInit tries to pull out an existing float64Histogram
+// from the value, but if none exists, then it allocates one with
+// the given buckets.
+func (v *metricValue) float64HistOrInit(buckets []float64) *metricFloat64Histogram {
+	var hist *metricFloat64Histogram
+	if v.kind == metricKindFloat64Histogram && v.pointer != nil {
+		hist = (*metricFloat64Histogram)(v.pointer)
+	} else {
+		v.kind = metricKindFloat64Histogram
+		hist = new(metricFloat64Histogram)
+		v.pointer = unsafe.Pointer(hist)
+	}
+	hist.buckets = buckets
+	if len(hist.counts) != len(hist.buckets)+1 {
+		hist.counts = make([]uint64, len(buckets)+1)
+	}
+	return hist
+}
+
+// metricFloat64Histogram is a runtime copy of runtime/metrics.Float64Histogram
+// and must be kept structurally identical to that type.
+type metricFloat64Histogram struct {
+	counts  []uint64
+	buckets []float64
+}
+
 // agg is used by readMetrics, and is protected by metricsSema.
 //
 // Managed as a global variable because its pointer will be
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index 66d229c270..e43904fc7d 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -68,6 +68,16 @@ var allDesc = []Description{
 		Kind:        KindUint64,
 		Cumulative:  true,
 	},
+	{
+		Name:        "/gc/heap/allocs-by-size:objects",
+		Description: "Distribution of all objects allocated by approximate size.",
+		Kind:        KindFloat64Histogram,
+	},
+	{
+		Name:        "/gc/heap/frees-by-size:objects",
+		Description: "Distribution of all objects freed by approximate size.",
+		Kind:        KindFloat64Histogram,
+	},
 	{
 		Name:        "/gc/heap/goal:bytes",
 		Description: "Heap size target for the end of the GC cycle.",
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index 9b44e73ee6..5045a5b4c1 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -53,6 +53,12 @@ Supported metrics
 	/gc/cycles/total:gc-cycles
 		Count of all completed GC cycles.
 
+	/gc/heap/allocs-by-size:objects
+		Distribution of all objects allocated by approximate size.
+
+	/gc/heap/frees-by-size:objects
+		Distribution of all objects freed by approximate size.
+
 	/gc/heap/goal:bytes
 		Heap size target for the end of the GC cycle.
 
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index 3724760294..1a30810544 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -98,6 +98,10 @@ func TestReadMetricsConsistency(t *testing.T) {
 	var totalVirtual struct {
 		got, want uint64
 	}
+	var objects struct {
+		alloc, free *metrics.Float64Histogram
+		total       uint64
+	}
 	for i := range samples {
 		kind := samples[i].Value.Kind()
 		if want := descs[samples[i].Name].Kind; kind != want {
@@ -118,11 +122,43 @@ func TestReadMetricsConsistency(t *testing.T) {
 		switch samples[i].Name {
 		case "/memory/classes/total:bytes":
 			totalVirtual.got = samples[i].Value.Uint64()
+		case "/gc/heap/objects:objects":
+			objects.total = samples[i].Value.Uint64()
+		case "/gc/heap/allocs-by-size:objects":
+			objects.alloc = samples[i].Value.Float64Histogram()
+		case "/gc/heap/frees-by-size:objects":
+			objects.free = samples[i].Value.Float64Histogram()
 		}
 	}
 	if totalVirtual.got != totalVirtual.want {
 		t.Errorf(`"/memory/classes/total:bytes" does not match sum of /memory/classes/**: got %d, want %d`, totalVirtual.got, totalVirtual.want)
 	}
+	if len(objects.alloc.Buckets) != len(objects.free.Buckets) {
+		t.Error("allocs-by-size and frees-by-size buckets don't match in length")
+	} else if len(objects.alloc.Counts) != len(objects.free.Counts) {
+		t.Error("allocs-by-size and frees-by-size counts don't match in length")
+	} else {
+		for i := range objects.alloc.Buckets {
+			ba := objects.alloc.Buckets[i]
+			bf := objects.free.Buckets[i]
+			if ba != bf {
+				t.Errorf("bucket %d is different for alloc and free hists: %f != %f", i, ba, bf)
+			}
+		}
+		if !t.Failed() {
+			got, want := uint64(0), objects.total
+			for i := range objects.alloc.Counts {
+				if objects.alloc.Counts[i] < objects.free.Counts[i] {
+					t.Errorf("found more allocs than frees in object dist bucket %d", i)
+					continue
+				}
+				got += objects.alloc.Counts[i] - objects.free.Counts[i]
+			}
+			if got != want {
+				t.Errorf("object distribution counts don't match count of live objects: got %d, want %d", got, want)
+			}
+		}
+	}
 }
 
 func BenchmarkReadMetricsLatency(b *testing.B) {
-- 
cgit v1.3


From 36c5edd8d9e6c13af26733e5c820eae0598203fe Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Thu, 6 Aug 2020 20:36:49 +0000
Subject: runtime: add timeHistogram type

This change adds a concurrent HDR time histogram to the runtime with
tests. It also adds a function to generate boundaries for use by the
metrics package.

For #37112.

Change-Id: Ifbef8ddce8e3a965a0dcd58ccd4915c282ae2098
Reviewed-on: https://go-review.googlesource.com/c/go/+/247046
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 src/runtime/export_test.go    |  24 +++++++
 src/runtime/histogram.go      | 148 ++++++++++++++++++++++++++++++++++++++++++
 src/runtime/histogram_test.go |  58 +++++++++++++++++
 src/runtime/metrics.go        |   2 +
 4 files changed, 232 insertions(+)
 create mode 100644 src/runtime/histogram.go
 create mode 100644 src/runtime/histogram_test.go

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/export_test.go b/src/runtime/export_test.go
index d043fe3ee5..4ca0420d2a 100644
--- a/src/runtime/export_test.go
+++ b/src/runtime/export_test.go
@@ -1141,3 +1141,27 @@ func MSpanCountAlloc(ms *MSpan, bits []byte) int {
 	s.gcmarkBits = nil
 	return result
 }
+
+const (
+	TimeHistSubBucketBits   = timeHistSubBucketBits
+	TimeHistNumSubBuckets   = timeHistNumSubBuckets
+	TimeHistNumSuperBuckets = timeHistNumSuperBuckets
+)
+
+type TimeHistogram timeHistogram
+
+// Counts returns the counts for the given bucket, subBucket indices.
+// Returns true if the bucket was valid, otherwise returns the counts
+// for the overflow bucket and false.
+func (th *TimeHistogram) Count(bucket, subBucket uint) (uint64, bool) {
+	t := (*timeHistogram)(th)
+	i := bucket*TimeHistNumSubBuckets + subBucket
+	if i >= uint(len(t.counts)) {
+		return t.overflow, false
+	}
+	return t.counts[i], true
+}
+
+func (th *TimeHistogram) Record(duration int64) {
+	(*timeHistogram)(th).record(duration)
+}
diff --git a/src/runtime/histogram.go b/src/runtime/histogram.go
new file mode 100644
index 0000000000..4020969eb9
--- /dev/null
+++ b/src/runtime/histogram.go
@@ -0,0 +1,148 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import (
+	"runtime/internal/atomic"
+	"runtime/internal/sys"
+)
+
+const (
+	// For the time histogram type, we use an HDR histogram.
+	// Values are placed in super-buckets based solely on the most
+	// significant set bit. Thus, super-buckets are power-of-2 sized.
+	// Values are then placed into sub-buckets based on the value of
+	// the next timeHistSubBucketBits most significant bits. Thus,
+	// sub-buckets are linear within a super-bucket.
+	//
+	// Therefore, the number of sub-buckets (timeHistNumSubBuckets)
+	// defines the error. This error may be computed as
+	// 1/timeHistNumSubBuckets*100%. For example, for 16 sub-buckets
+	// per super-bucket the error is approximately 6%.
+	//
+	// The number of super-buckets (timeHistNumSuperBuckets), on the
+	// other hand, defines the range. To reserve room for sub-buckets,
+	// bit timeHistSubBucketBits is the first bit considered for
+	// super-buckets, so super-bucket indicies are adjusted accordingly.
+	//
+	// As an example, consider 45 super-buckets with 16 sub-buckets.
+	//
+	//    00110
+	//    ^----
+	//    │  ^
+	//    │  └---- Lowest 4 bits -> sub-bucket 6
+	//    └------- Bit 4 unset -> super-bucket 0
+	//
+	//    10110
+	//    ^----
+	//    │  ^
+	//    │  └---- Next 4 bits -> sub-bucket 6
+	//    └------- Bit 4 set -> super-bucket 1
+	//    100010
+	//    ^----^
+	//    │  ^ └-- Lower bits ignored
+	//    │  └---- Next 4 bits -> sub-bucket 1
+	//    └------- Bit 5 set -> super-bucket 2
+	//
+	// Following this pattern, bucket 45 will have the bit 48 set. We don't
+	// have any buckets for higher values, so the highest sub-bucket will
+	// contain values of 2^48-1 nanoseconds or approx. 3 days. This range is
+	// more than enough to handle durations produced by the runtime.
+	timeHistSubBucketBits   = 4
+	timeHistNumSubBuckets   = 1 << timeHistSubBucketBits
+	timeHistNumSuperBuckets = 45
+	timeHistTotalBuckets    = timeHistNumSuperBuckets*timeHistNumSubBuckets + 1
+)
+
+// timeHistogram represents a distribution of durations in
+// nanoseconds.
+//
+// The accuracy and range of the histogram is defined by the
+// timeHistSubBucketBits and timeHistNumSuperBuckets constants.
+//
+// It is an HDR histogram with exponentially-distributed
+// buckets and linearly distributed sub-buckets.
+//
+// Counts in the histogram are updated atomically, so it is safe
+// for concurrent use. It is also safe to read all the values
+// atomically.
+type timeHistogram struct {
+	counts   [timeHistNumSuperBuckets * timeHistNumSubBuckets]uint64
+	overflow uint64
+}
+
+// record adds the given duration to the distribution.
+//
+// Although the duration is an int64 to facilitate ease-of-use
+// with e.g. nanotime, the duration must be non-negative.
+func (h *timeHistogram) record(duration int64) {
+	if duration < 0 {
+		throw("timeHistogram encountered negative duration")
+	}
+	// The index of the exponential bucket is just the index
+	// of the highest set bit adjusted for how many bits we
+	// use for the subbucket. Note that it's timeHistSubBucketsBits-1
+	// because we use the 0th bucket to hold values < timeHistNumSubBuckets.
+	var superBucket, subBucket uint
+	if duration >= timeHistNumSubBuckets {
+		// At this point, we know the duration value will always be
+		// at least timeHistSubBucketsBits long.
+		superBucket = uint(sys.Len64(uint64(duration))) - timeHistSubBucketBits
+		if superBucket*timeHistNumSubBuckets >= uint(len(h.counts)) {
+			// The bucket index we got is larger than what we support, so
+			// add into the special overflow bucket.
+			atomic.Xadd64(&h.overflow, 1)
+			return
+		}
+		// The linear subbucket index is just the timeHistSubBucketsBits
+		// bits after the top bit. To extract that value, shift down
+		// the duration such that we leave the top bit and the next bits
+		// intact, then extract the index.
+		subBucket = uint((duration >> (superBucket - 1)) % timeHistNumSubBuckets)
+	} else {
+		subBucket = uint(duration)
+	}
+	atomic.Xadd64(&h.counts[superBucket*timeHistNumSubBuckets+subBucket], 1)
+}
+
+// timeHistogramMetricsBuckets generates a slice of boundaries for
+// the timeHistogram. These boundaries are represented in seconds,
+// not nanoseconds like the timeHistogram represents durations.
+func timeHistogramMetricsBuckets() []float64 {
+	b := make([]float64, timeHistTotalBuckets-1)
+	for i := 0; i < timeHistNumSuperBuckets; i++ {
+		superBucketMin := uint64(0)
+		// The (inclusive) minimum for the first bucket is 0.
+		if i > 0 {
+			// The minimum for the second bucket will be
+			// 1 << timeHistSubBucketBits, indicating that all
+			// sub-buckets are represented by the next timeHistSubBucketBits
+			// bits.
+			// Thereafter, we shift up by 1 each time, so we can represent
+			// this pattern as (i-1)+timeHistSubBucketBits.
+			superBucketMin = uint64(1) << uint(i-1+timeHistSubBucketBits)
+		}
+		// subBucketShift is the amount that we need to shift the sub-bucket
+		// index to combine it with the bucketMin.
+		subBucketShift := uint(0)
+		if i > 1 {
+			// The first two buckets are exact with respect to integers,
+			// so we'll never have to shift the sub-bucket index. Thereafter,
+			// we shift up by 1 with each subsequent bucket.
+			subBucketShift = uint(i - 2)
+		}
+		for j := 0; j < timeHistNumSubBuckets; j++ {
+			// j is the sub-bucket index. By shifting the index into position to
+			// combine with the bucket minimum, we obtain the minimum value for that
+			// sub-bucket.
+			subBucketMin := superBucketMin + (uint64(j) << subBucketShift)
+
+			// Convert the subBucketMin which is in nanoseconds to a float64 seconds value.
+			// These values will all be exactly representable by a float64.
+			b[i*timeHistNumSubBuckets+j] = float64(subBucketMin) / 1e9
+		}
+	}
+	return b
+}
diff --git a/src/runtime/histogram_test.go b/src/runtime/histogram_test.go
new file mode 100644
index 0000000000..5f5b28f784
--- /dev/null
+++ b/src/runtime/histogram_test.go
@@ -0,0 +1,58 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	. "runtime"
+	"testing"
+)
+
+var dummyTimeHistogram TimeHistogram
+
+func TestTimeHistogram(t *testing.T) {
+	// We need to use a global dummy because this
+	// could get stack-allocated with a non-8-byte alignment.
+	// The result of this bad alignment is a segfault on
+	// 32-bit platforms when calling Record.
+	h := &dummyTimeHistogram
+
+	// Record exactly one sample in each bucket.
+	for i := 0; i < TimeHistNumSuperBuckets; i++ {
+		var base int64
+		if i > 0 {
+			base = int64(1) << (i + TimeHistSubBucketBits - 1)
+		}
+		for j := 0; j < TimeHistNumSubBuckets; j++ {
+			v := int64(j)
+			if i > 0 {
+				v <<= i - 1
+			}
+			h.Record(base + v)
+		}
+	}
+	// Hit the overflow bucket.
+	h.Record(int64(^uint64(0) >> 1))
+
+	// Check to make sure there's exactly one count in each
+	// bucket.
+	for i := uint(0); i < TimeHistNumSuperBuckets; i++ {
+		for j := uint(0); j < TimeHistNumSubBuckets; j++ {
+			c, ok := h.Count(i, j)
+			if !ok {
+				t.Errorf("hit overflow bucket unexpectedly: (%d, %d)", i, j)
+			} else if c != 1 {
+				t.Errorf("bucket (%d, %d) has count that is not 1: %d", i, j, c)
+			}
+		}
+	}
+	c, ok := h.Count(TimeHistNumSuperBuckets, 0)
+	if ok {
+		t.Errorf("expected to hit overflow bucket: (%d, %d)", TimeHistNumSuperBuckets, 0)
+	}
+	if c != 1 {
+		t.Errorf("overflow bucket has count that is not 1: %d", c)
+	}
+	dummyTimeHistogram = TimeHistogram{}
+}
diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 32d8ab461c..2be38ccaaa 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -20,6 +20,7 @@ var (
 	metrics     map[string]metricData
 
 	sizeClassBuckets []float64
+	timeHistBuckets  []float64
 )
 
 type metricData struct {
@@ -44,6 +45,7 @@ func initMetrics() {
 	for i := range sizeClassBuckets {
 		sizeClassBuckets[i] = float64(class_to_size[i])
 	}
+	timeHistBuckets = timeHistogramMetricsBuckets()
 	metrics = map[string]metricData{
 		"/gc/cycles/automatic:gc-cycles": {
 			deps: makeStatDepSet(sysStatsDep),
-- 
cgit v1.3


From d39a89fd5843f535d634620d27110b320431f584 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Thu, 6 Aug 2020 21:59:13 +0000
Subject: runtime,runtime/metrics: add metric for distribution of GC pauses

For #37112.

Change-Id: Ibb0425c9c582ae3da3b2662d5bbe830d7df9079c
Reviewed-on: https://go-review.googlesource.com/c/go/+/247047
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 src/runtime/metrics.go             |  9 +++++++++
 src/runtime/metrics/description.go |  5 +++++
 src/runtime/metrics/doc.go         |  3 +++
 src/runtime/metrics_test.go        | 22 ++++++++++++++++++++++
 src/runtime/mgc.go                 |  3 +++
 src/runtime/mstats.go              | 12 ++++++++++++
 6 files changed, 54 insertions(+)

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 2be38ccaaa..0e391472b2 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -102,6 +102,15 @@ func initMetrics() {
 				out.scalar = in.heapStats.numObjects
 			},
 		},
+		"/gc/pauses:seconds": {
+			compute: func(_ *statAggregate, out *metricValue) {
+				hist := out.float64HistOrInit(timeHistBuckets)
+				hist.counts[len(hist.counts)-1] = atomic.Load64(&memstats.gcPauseDist.overflow)
+				for i := range hist.buckets {
+					hist.counts[i] = atomic.Load64(&memstats.gcPauseDist.counts[i])
+				}
+			},
+		},
 		"/memory/classes/heap/free:bytes": {
 			deps: makeStatDepSet(heapStatsDep),
 			compute: func(in *statAggregate, out *metricValue) {
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index e43904fc7d..47959e467c 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -88,6 +88,11 @@ var allDesc = []Description{
 		Description: "Number of objects, live or unswept, occupying heap memory.",
 		Kind:        KindUint64,
 	},
+	{
+		Name:        "/gc/pauses:seconds",
+		Description: "Distribution individual GC-related stop-the-world pause latencies.",
+		Kind:        KindFloat64Histogram,
+	},
 	{
 		Name:        "/memory/classes/heap/free:bytes",
 		Description: "Memory that is available for allocation, and may be returned to the underlying system.",
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index 5045a5b4c1..1e12ade5a1 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -65,6 +65,9 @@ Supported metrics
 	/gc/heap/objects:objects
 		Number of objects, live or unswept, occupying heap memory.
 
+	/gc/pauses:seconds
+		Distribution individual GC-related stop-the-world pause latencies.
+
 	/memory/classes/heap/free:bytes
 		Memory that is available for allocation, and may be returned
 		to the underlying system.
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index 1a30810544..7b3132bc30 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -90,6 +90,11 @@ func TestReadMetricsConsistency(t *testing.T) {
 	// things (e.g. allocating) so what we read can't reasonably compared
 	// to runtime values.
 
+	// Run a few GC cycles to get some of the stats to be non-zero.
+	runtime.GC()
+	runtime.GC()
+	runtime.GC()
+
 	// Read all the supported metrics through the metrics package.
 	descs, samples := prepareAllMetricsSamples()
 	metrics.Read(samples)
@@ -102,6 +107,10 @@ func TestReadMetricsConsistency(t *testing.T) {
 		alloc, free *metrics.Float64Histogram
 		total       uint64
 	}
+	var gc struct {
+		numGC  uint64
+		pauses uint64
+	}
 	for i := range samples {
 		kind := samples[i].Value.Kind()
 		if want := descs[samples[i].Name].Kind; kind != want {
@@ -128,6 +137,14 @@ func TestReadMetricsConsistency(t *testing.T) {
 			objects.alloc = samples[i].Value.Float64Histogram()
 		case "/gc/heap/frees-by-size:objects":
 			objects.free = samples[i].Value.Float64Histogram()
+		case "/gc/cycles:gc-cycles":
+			gc.numGC = samples[i].Value.Uint64()
+		case "/gc/pauses:seconds":
+			h := samples[i].Value.Float64Histogram()
+			gc.pauses = 0
+			for i := range h.Counts {
+				gc.pauses += h.Counts[i]
+			}
 		}
 	}
 	if totalVirtual.got != totalVirtual.want {
@@ -159,6 +176,11 @@ func TestReadMetricsConsistency(t *testing.T) {
 			}
 		}
 	}
+	// The current GC has at least 2 pauses per GC.
+	// Check to see if that value makes sense.
+	if gc.pauses < gc.numGC*2 {
+		t.Errorf("fewer pauses than expected: got %d, want at least %d", gc.pauses, gc.numGC*2)
+	}
 }
 
 func BenchmarkReadMetricsLatency(b *testing.B) {
diff --git a/src/runtime/mgc.go b/src/runtime/mgc.go
index 540c376f1c..b0ab0ae6bb 100644
--- a/src/runtime/mgc.go
+++ b/src/runtime/mgc.go
@@ -1418,6 +1418,7 @@ func gcStart(trigger gcTrigger) {
 		now = startTheWorldWithSema(trace.enabled)
 		work.pauseNS += now - work.pauseStart
 		work.tMark = now
+		memstats.gcPauseDist.record(now - work.pauseStart)
 	})
 
 	// Release the world sema before Gosched() in STW mode
@@ -1565,6 +1566,7 @@ top:
 		systemstack(func() {
 			now := startTheWorldWithSema(true)
 			work.pauseNS += now - work.pauseStart
+			memstats.gcPauseDist.record(now - work.pauseStart)
 		})
 		semrelease(&worldsema)
 		goto top
@@ -1677,6 +1679,7 @@ func gcMarkTermination(nextTriggerRatio float64) {
 	unixNow := sec*1e9 + int64(nsec)
 	work.pauseNS += now - work.pauseStart
 	work.tEnd = now
+	memstats.gcPauseDist.record(now - work.pauseStart)
 	atomic.Store64(&memstats.last_gc_unix, uint64(unixNow)) // must be Unix time to make sense to user
 	atomic.Store64(&memstats.last_gc_nanotime, uint64(now)) // monotonic time for us
 	memstats.pause_ns[memstats.numgc%uint32(len(memstats.pause_ns))] = uint64(work.pauseNS)
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go
index 07f466ec49..e0a417d213 100644
--- a/src/runtime/mstats.go
+++ b/src/runtime/mstats.go
@@ -157,6 +157,14 @@ type mstats struct {
 
 	// heapStats is a set of statistics
 	heapStats consistentHeapStats
+
+	_ uint32 // ensure gcPauseDist is aligned
+
+	// gcPauseDist represents the distribution of all GC-related
+	// application pauses in the runtime.
+	//
+	// Each individual pause is counted separately, unlike pause_ns.
+	gcPauseDist timeHistogram
 }
 
 var memstats mstats
@@ -443,6 +451,10 @@ func init() {
 		println(offset)
 		throw("memstats.heapStats not aligned to 8 bytes")
 	}
+	if offset := unsafe.Offsetof(memstats.gcPauseDist); offset%8 != 0 {
+		println(offset)
+		throw("memstats.gcPauseDist not aligned to 8 bytes")
+	}
 	// Ensure the size of heapStatsDelta causes adjacent fields/slots (e.g.
 	// [3]heapStatsDelta) to be 8-byte aligned.
 	if size := unsafe.Sizeof(heapStatsDelta{}); size%8 != 0 {
-- 
cgit v1.3


From 80c6b92ecb911409f57d06793a1213395b75ebe2 Mon Sep 17 00:00:00 2001
From: Michael Anthony Knyszek <mknyszek@google.com>
Date: Fri, 7 Aug 2020 16:37:29 +0000
Subject: runtime,runtime/metrics: export goroutine count as a metric

For #37112.

Change-Id: I994dfe848605b95ef6aec24f53869e929247e987
Reviewed-on: https://go-review.googlesource.com/c/go/+/247049
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
---
 src/runtime/metrics.go             | 6 ++++++
 src/runtime/metrics/description.go | 5 +++++
 src/runtime/metrics/doc.go         | 3 +++
 src/runtime/metrics_test.go        | 4 ++++
 4 files changed, 18 insertions(+)

(limited to 'src/runtime/metrics.go')

diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 0e391472b2..d3c0341aee 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -214,6 +214,12 @@ func initMetrics() {
 					in.sysStats.gcMiscSys + in.sysStats.otherSys
 			},
 		},
+		"/sched/goroutines:goroutines": {
+			compute: func(_ *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(gcount())
+			},
+		},
 	}
 	metricsInit = true
 }
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index 47959e467c..bc2e0882db 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -163,6 +163,11 @@ var allDesc = []Description{
 		Description: "All memory mapped by the Go runtime into the current process as read-write. Note that this does not include memory mapped by code called via cgo or via the syscall package. Sum of all metrics in /memory/classes.",
 		Kind:        KindUint64,
 	},
+	{
+		Name:        "/sched/goroutines:goroutines",
+		Description: "Count of live goroutines.",
+		Kind:        KindUint64,
+	},
 }
 
 // All returns a slice of containing metric descriptions for all supported metrics.
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index 1e12ade5a1..e340f3d0dd 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -123,5 +123,8 @@ Supported metrics
 		as read-write. Note that this does not include memory mapped
 		by code called via cgo or via the syscall package.
 		Sum of all metrics in /memory/classes.
+
+	/sched/goroutines:goroutines
+		Count of live goroutines.
 */
 package metrics
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index 7b3132bc30..167edd57fd 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -145,6 +145,10 @@ func TestReadMetricsConsistency(t *testing.T) {
 			for i := range h.Counts {
 				gc.pauses += h.Counts[i]
 			}
+		case "/sched/goroutines:goroutines":
+			if samples[i].Value.Uint64() < 1 {
+				t.Error("number of goroutines is less than one")
+			}
 		}
 	}
 	if totalVirtual.got != totalVirtual.want {
-- 
cgit v1.3