Copy metrics for each configured output

This is for better thread-safety when running with multiple outputs,
which can cause very odd panics at very high loads

primarily this is to address #1432

Makefile

@@ -25,10 +25,6 @@ build-for-docker:
 					"-s -X main.version=$(VERSION)" \
 					./cmd/telegraf/telegraf.go
 
-# Build with race detector
-dev: prepare
-	go build -race -ldflags "-X main.version=$(VERSION)" ./...
-
 # run package script
 package:
 	./scripts/build.py --package --version="$(VERSION)" --platform=linux --arch=all --upload

agent/agent.go

@@ -268,13 +268,33 @@ func (a *Agent) flusher(shutdown chan struct{}, metricC chan telegraf.Metric) er
 			internal.RandomSleep(a.Config.Agent.FlushJitter.Duration, shutdown)
 			a.flush()
 		case m := <-metricC:
-			for _, o := range a.Config.Outputs {
+			if len(a.Config.Outputs) > 1 {
+				for _, o := range a.Config.Outputs {
+					o.AddMetric(copyMetric(m))
+				}
+			} else {
 				o.AddMetric(m)
 			}
 		}
 	}
 }
 
+func copyMetric(m telegraf.Metric) telegraf.Metric {
+	t := time.Time(m.Time())
+
+	tags := make(map[string]string)
+	fields := make(map[string]interface{})
+	for k, v := range m.Tags() {
+		tags[k] = v
+	}
+	for k, v := range m.Fields() {
+		fields[k] = v
+	}
+
+	out, _ := telegraf.NewMetric(m.Name(), tags, fields, t)
+	return out
+}
+
 // Run runs the agent daemon, gathering every Interval
 func (a *Agent) Run(shutdown chan struct{}) error {
 	var wg sync.WaitGroup

plugins/inputs/tcp_listener/tcp_listener.go

@@ -31,6 +31,8 @@ type TcpListener struct {
 	accept chan bool
 	// drops tracks the number of dropped metrics.
 	drops int
+	// malformed tracks the number of malformed packets
+	malformed int
 
 	// track the listener here so we can close it in Stop()
 	listener *net.TCPListener
@@ -45,6 +47,9 @@ var dropwarn = "ERROR: tcp_listener message queue full. " +
 	"We have dropped %d messages so far. " +
 	"You may want to increase allowed_pending_messages in the config\n"
 
+var malformedwarn = "WARNING: tcp_listener has received %d malformed packets" +
+	" thus far."
+
 const sampleConfig = `
   ## Address and port to host TCP listener on
   service_address = ":8094"
@@ -243,8 +248,10 @@ func (t *TcpListener) tcpParser() error {
 			if err == nil {
 				t.storeMetrics(metrics)
 			} else {
-				log.Printf("Malformed packet: [%s], Error: %s\n",
-					string(packet), err)
+				t.malformed++
+				if t.malformed == 1 || t.malformed%1000 == 0 {
+					log.Printf(malformedwarn, t.malformed)
+				}
 			}
 		}
 	}

plugins/inputs/udp_listener/udp_listener.go

@@ -27,6 +27,8 @@ type UdpListener struct {
 	done chan struct{}
 	// drops tracks the number of dropped metrics.
 	drops int
+	// malformed tracks the number of malformed packets
+	malformed int
 
 	parser parsers.Parser
 
@@ -44,6 +46,9 @@ var dropwarn = "ERROR: udp_listener message queue full. " +
 	"We have dropped %d messages so far. " +
 	"You may want to increase allowed_pending_messages in the config\n"
 
+var malformedwarn = "WARNING: udp_listener has received %d malformed packets" +
+	" thus far."
+
 const sampleConfig = `
   ## Address and port to host UDP listener on
   service_address = ":8092"
@@ -152,7 +157,10 @@ func (u *UdpListener) udpParser() error {
 			if err == nil {
 				u.storeMetrics(metrics)
 			} else {
-				log.Printf("Malformed packet: [%s], Error: %s\n", packet, err)
+				u.malformed++
+				if u.malformed == 1 || u.malformed%1000 == 0 {
+					log.Printf(malformedwarn, u.malformed)
+				}
 			}
 		}
 	}

plugins/serializers/graphite/graphite.go

@@ -20,7 +20,7 @@ type GraphiteSerializer struct {
 	Template string
 }
 
-func (s GraphiteSerializer) Serialize(metric telegraf.Metric) ([]string, error) {
+func (s *GraphiteSerializer) Serialize(metric telegraf.Metric) ([]string, error) {
 	out := []string{}
 
 	// Convert UnixNano to Unix timestamps