Cherry-pick #11263 to 6.7: Stop waiting for signals on closed outleters

CHANGELOG.next.asciidoc

@@ -46,6 +46,7 @@ https://github.com/elastic/beats/compare/v6.7.0...6.x[Check the HEAD diff]
 
 *Filebeat*
 
+- Fix goroutine leak happening when harvesters are dynamically stopped. {pull}11263[11263]
 - Don't apply multiline rules in Logstash json logs. {pull}11346[11346]
 
 *Heartbeat*

filebeat/channel/interface.go

@@ -32,5 +32,6 @@ type Connector func(*common.Config, *common.MapStrPointer) (Outleter, error)
 // Outleter is the outlet for an input
 type Outleter interface {
 	Close() error
+	Done() <-chan struct{}
 	OnEvent(data *util.Data) bool
 }

filebeat/channel/outlet.go

@@ -27,25 +27,32 @@ type outlet struct {
 	wg     eventCounter
 	client beat.Client
 	isOpen atomic.Bool
+	done   chan struct{}
 }
 
 func newOutlet(client beat.Client, wg eventCounter) *outlet {
 	o := &outlet{
 		wg:     wg,
 		client: client,
 		isOpen: atomic.MakeBool(true),
+		done:   make(chan struct{}),
 	}
 	return o
 }
 
 func (o *outlet) Close() error {
 	isOpen := o.isOpen.Swap(false)
 	if isOpen {
+		close(o.done)
 		return o.client.Close()
 	}
 	return nil
 }
 
+func (o *outlet) Done() <-chan struct{} {
+	return o.done
+}
+
 func (o *outlet) OnEvent(d *util.Data) bool {
 	if !o.isOpen.Load() {
 		return false

filebeat/channel/util.go

@@ -71,6 +71,10 @@ func (o *subOutlet) Close() error {
 	return nil
 }
 
+func (o *subOutlet) Done() <-chan struct{} {
+	return o.done
+}
+
 func (o *subOutlet) OnEvent(d *util.Data) bool {
 
 	o.mutex.Lock()
@@ -114,8 +118,12 @@ func (o *subOutlet) OnEvent(d *util.Data) bool {
 func CloseOnSignal(outlet Outleter, sig <-chan struct{}) Outleter {
 	if sig != nil {
 		go func() {
-			<-sig
-			outlet.Close()
+			select {
+			case <-outlet.Done():
+				return
+			case <-sig:
+				outlet.Close()
+			}
 		}()
 	}
 	return outlet

filebeat/input/log/input_other_test.go

@@ -169,3 +169,4 @@ type TestOutlet struct{}
 
 func (o TestOutlet) OnEvent(event *util.Data) bool { return true }
 func (o TestOutlet) Close() error                  { return nil }
+func (o TestOutlet) Done() <-chan struct{}         { return nil }