fix deadlock collecting large logs

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

pkg/compose/printer.go

@@ -32,18 +32,19 @@ type logPrinter interface {
 }
 
 type printer struct {
-	sync.Mutex
 	queue    chan api.ContainerEvent
 	consumer api.LogConsumer
-	stopped  bool
+	stopCh   chan struct{}
+	stop     sync.Once
 }
 
 // newLogPrinter builds a LogPrinter passing containers logs to LogConsumer
 func newLogPrinter(consumer api.LogConsumer) logPrinter {
-	queue := make(chan api.ContainerEvent)
 	printer := printer{
 		consumer: consumer,
-		queue:    queue,
+		queue:    make(chan api.ContainerEvent),
+		stopCh:   make(chan struct{}),
+		stop:     sync.Once{},
 	}
 	return &printer
 }
@@ -54,24 +55,26 @@ func (p *printer) Cancel() {
 }
 
 func (p *printer) Stop() {
-	p.Lock()
-	defer p.Unlock()
-	if !p.stopped {
-		// only close if this is the first call to stop
-		p.stopped = true
-		close(p.queue)
-	}
+	p.stop.Do(func() {
+		close(p.stopCh)
+		for {
+			select {
+			case <-p.queue:
+				// purge the queue
+			default:
+				return
+			}
+		}
+	})
 }
 
 func (p *printer) HandleEvent(event api.ContainerEvent) {
-	p.Lock()
-	defer p.Unlock()
-	if p.stopped {
-		// prevent deadlocking, if the printer is done, there's no reader for
-		// queue, so this write could block indefinitely
+	select {
+	case <-p.stopCh:
 		return
+	default:
+		p.queue <- event
 	}
-	p.queue <- event
 }
 
 //nolint:gocyclo
@@ -80,6 +83,8 @@ func (p *printer) Run(cascadeStop bool, exitCodeFrom string, stopFn func() error
 		aborting bool
 		exitCode int
 	)
+	defer p.Stop()
+
 	containers := map[string]struct{}{}
 	for event := range p.queue {
 		container, id := event.Container, event.ID