telemetry: Add memory and goroutine metrics, rename container

And fix a typo in a comment, sigh

telemetry/telemetry.go

@@ -40,6 +40,7 @@ import (
 	"log"
 	"math/rand"
 	"net/http"
+	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -66,6 +67,9 @@ func emit(final bool) error {
 		return fmt.Errorf("telemetry not enabled")
 	}
 
+	// some metrics are updated/set at time of emission
+	setEmitTimeMetrics()
+
 	// ensure only one update happens at a time;
 	// skip update if previous one still in progress
 	updateMu.Lock()
@@ -228,6 +232,17 @@ func stopUpdateTimer() {
 	updateTimerMu.Unlock()
 }
 
+// setEmitTimeMetrics sets some metrics that should
+// be recorded just before emitting.
+func setEmitTimeMetrics() {
+	Set("goroutines", runtime.NumGoroutine())
+
+	var mem runtime.MemStats
+	runtime.ReadMemStats(&mem)
+	SetNested("memory", "heap_alloc", mem.HeapAlloc)
+	SetNested("memory", "sys", mem.Sys)
+}
+
 // makePayloadAndResetBuffer prepares a payload
 // by emptying the collection buffer. It returns
 // the bytes of the payload to send to the server.