Close UDP listener in udp_listener plugin

also adding waitgroups to udp_listener and statsd plugins to verify that
all goroutines have been cleaned up before Stop() exits.

closes #869

plugins/inputs/statsd/statsd.go

@@ -50,6 +50,7 @@ type Statsd struct {
 	UDPPacketSize int `toml:"udp_packet_size"`
 
 	sync.Mutex
+	wg sync.WaitGroup
 
 	// Channel for all incoming statsd packets
 	in   chan []byte
@@ -238,6 +239,7 @@ func (s *Statsd) Start(_ telegraf.Accumulator) error {
 	s.sets = make(map[string]cachedset)
 	s.timings = make(map[string]cachedtimings)
 
+	s.wg.Add(2)
 	// Start the UDP listener
 	go s.udpListen()
 	// Start the line parser
@@ -248,13 +250,13 @@ func (s *Statsd) Start(_ telegraf.Accumulator) error {
 
 // udpListen starts listening for udp packets on the configured port.
 func (s *Statsd) udpListen() error {
+	defer s.wg.Done()
 	var err error
 	address, _ := net.ResolveUDPAddr("udp", s.ServiceAddress)
 	s.listener, err = net.ListenUDP("udp", address)
 	if err != nil {
 		log.Fatalf("ERROR: ListenUDP - %s", err)
 	}
-	defer s.listener.Close()
 	log.Println("Statsd listener listening on: ", s.listener.LocalAddr().String())
 
 	for {
@@ -264,7 +266,7 @@ func (s *Statsd) udpListen() error {
 		default:
 			buf := make([]byte, s.UDPPacketSize)
 			n, _, err := s.listener.ReadFromUDP(buf)
-			if err != nil {
+			if err != nil && !strings.Contains(err.Error(), "closed network") {
 				log.Printf("ERROR READ: %s\n", err.Error())
 				continue
 			}
@@ -282,6 +284,7 @@ func (s *Statsd) udpListen() error {
 // packet into statsd strings and then calls parseStatsdLine, which parses a
 // single statsd metric into a struct.
 func (s *Statsd) parser() error {
+	defer s.wg.Done()
 	for {
 		select {
 		case <-s.done:
@@ -561,8 +564,9 @@ func (s *Statsd) Stop() {
 	s.Lock()
 	defer s.Unlock()
 	log.Println("Stopping the statsd service")
-	s.listener.Close()
 	close(s.done)
+	s.listener.Close()
+	s.wg.Wait()
 	close(s.in)
 }
 

plugins/inputs/udp_listener/udp_listener.go

@@ -3,6 +3,7 @@ package udp_listener
 import (
 	"log"
 	"net"
+	"strings"
 	"sync"
 
 	"github.com/influxdata/telegraf"
@@ -14,7 +15,9 @@ type UdpListener struct {
 	ServiceAddress         string
 	UDPPacketSize          int `toml:"udp_packet_size"`
 	AllowedPendingMessages int
+
 	sync.Mutex
+	wg sync.WaitGroup
 
 	in   chan []byte
 	done chan struct{}
@@ -23,6 +26,8 @@ type UdpListener struct {
 
 	// Keep the accumulator in this struct
 	acc telegraf.Accumulator
+
+	listener *net.UDPConn
 }
 
 const UDP_PACKET_SIZE int = 1500
@@ -76,6 +81,7 @@ func (u *UdpListener) Start(acc telegraf.Accumulator) error {
 	u.in = make(chan []byte, u.AllowedPendingMessages)
 	u.done = make(chan struct{})
 
+	u.wg.Add(2)
 	go u.udpListen()
 	go u.udpParser()
 
@@ -87,28 +93,32 @@ func (u *UdpListener) Stop() {
 	u.Lock()
 	defer u.Unlock()
 	close(u.done)
+	u.listener.Close()
+	u.wg.Wait()
 	close(u.in)
 	log.Println("Stopped UDP listener service on ", u.ServiceAddress)
 }
 
 func (u *UdpListener) udpListen() error {
+	defer u.wg.Done()
+	var err error
 	address, _ := net.ResolveUDPAddr("udp", u.ServiceAddress)
-	listener, err := net.ListenUDP("udp", address)
+	u.listener, err = net.ListenUDP("udp", address)
 	if err != nil {
 		log.Fatalf("ERROR: ListenUDP - %s", err)
 	}
-	defer listener.Close()
-	log.Println("UDP server listening on: ", listener.LocalAddr().String())
+	log.Println("UDP server listening on: ", u.listener.LocalAddr().String())
 
 	for {
 		select {
 		case <-u.done:
 			return nil
 		default:
 			buf := make([]byte, u.UDPPacketSize)
-			n, _, err := listener.ReadFromUDP(buf)
-			if err != nil {
+			n, _, err := u.listener.ReadFromUDP(buf)
+			if err != nil && !strings.Contains(err.Error(), "closed network") {
 				log.Printf("ERROR: %s\n", err.Error())
+				continue
 			}
 
 			select {
@@ -121,6 +131,7 @@ func (u *UdpListener) udpListen() error {
 }
 
 func (u *UdpListener) udpParser() error {
+	defer u.wg.Done()
 	for {
 		select {
 		case <-u.done:

plugins/inputs/udp_listener/udp_listener_test.go

@@ -32,6 +32,7 @@ func TestRunParser(t *testing.T) {
 	defer close(listener.done)
 
 	listener.parser, _ = parsers.NewInfluxParser()
+	listener.wg.Add(1)
 	go listener.udpParser()
 
 	in <- testmsg
@@ -58,6 +59,7 @@ func TestRunParserInvalidMsg(t *testing.T) {
 	defer close(listener.done)
 
 	listener.parser, _ = parsers.NewInfluxParser()
+	listener.wg.Add(1)
 	go listener.udpParser()
 
 	in <- testmsg
@@ -78,6 +80,7 @@ func TestRunParserGraphiteMsg(t *testing.T) {
 	defer close(listener.done)
 
 	listener.parser, _ = parsers.NewGraphiteParser("_", []string{}, nil)
+	listener.wg.Add(1)
 	go listener.udpParser()
 
 	in <- testmsg
@@ -98,6 +101,7 @@ func TestRunParserJSONMsg(t *testing.T) {
 	defer close(listener.done)
 
 	listener.parser, _ = parsers.NewJSONParser("udp_json_test", []string{}, nil)
+	listener.wg.Add(1)
 	go listener.udpParser()
 
 	in <- testmsg