Add NextGC

next collection will happen when HeapAlloc ≥ NextGC value

Author: taylorchu

runtime/doc.go

@@ -12,6 +12,7 @@
 //     Mem.NumGC
 //     Mem.PauseTotalNs
 //     Mem.LastGC
+//     Mem.NextGC
 //     Mem.Alloc
 //     Mem.HeapObjects
 //     Goroutines.Num

runtime/memstats.go

@@ -15,6 +15,7 @@ func init() {
 	metrics.Gauge("Mem.LastGC").SetBatchFunc(key{}, msg.init, msg.lastPause)
 	metrics.Gauge("Mem.Alloc").SetBatchFunc(key{}, msg.init, msg.alloc)
 	metrics.Gauge("Mem.HeapObjects").SetBatchFunc(key{}, msg.init, msg.objects)
+	metrics.Gauge("Mem.NextGC").SetBatchFunc(key{}, msg.init, msg.nextGC)
 }
 
 type key struct{} // unexported to prevent collision
@@ -46,3 +47,7 @@ func (msg *memStatGauges) alloc() int64 {
 func (msg *memStatGauges) objects() int64 {
 	return int64(msg.stats.HeapObjects)
 }
+
+func (msg *memStatGauges) nextGC() int64 {
+	return int64(msg.stats.NextGC)
+}

runtime/memstats_test.go

@@ -18,6 +18,7 @@ func TestMemStats(t *testing.T) {
 		"Mem.LastGC",
 		"Mem.Alloc",
 		"Mem.HeapObjects",
+		"Mem.NextGC",
 	}
 
 	for _, name := range expectedCounters {