Merge pull request #1005 from dgageot/fix-1004

Debounce rapid file changes

cmd/skaffold/app/cmd/cmd.go

@@ -135,6 +135,7 @@ func setFlagsFromEnvVariables(commands []*cobra.Command) {
 func AddDevFlags(cmd *cobra.Command) {
 	cmd.Flags().BoolVar(&opts.Cleanup, "cleanup", true, "Delete deployments after dev mode is interrupted")
 	cmd.Flags().StringArrayVarP(&opts.Watch, "watch-image", "w", nil, "Choose which artifacts to watch. Artifacts with image names that contain the expression will be watched only. Default is to watch sources for all artifacts.")
+	cmd.Flags().IntVarP(&opts.WatchPollInterval, "watch-poll-interval", "i", 1000, "Interval (in ms) between two checks for file changes.")
 }
 
 func AddRunDeployFlags(cmd *cobra.Command) {

pkg/skaffold/config/options.go

@@ -31,6 +31,7 @@ type SkaffoldOptions struct {
 	CustomTag         string
 	Namespace         string
 	Watch             []string
+	WatchPollInterval int
 }
 
 // Labels returns a map of labels to be applied to all deployed

pkg/skaffold/runner/runner.go

@@ -44,8 +44,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-const PollInterval = 1000 * time.Millisecond
-
 // ErrorConfigurationChanged is a special error that's returned when the skaffold configuration was changed.
 var ErrorConfigurationChanged = errors.New("configuration changed")
 
@@ -315,7 +313,8 @@ func (r *SkaffoldRunner) Dev(ctx context.Context, out io.Writer, artifacts []*v1
 		return nil, errors.Wrap(err, "starting port-forwarder")
 	}
 
-	return nil, watcher.Run(ctx, PollInterval, onChange)
+	pollInterval := time.Duration(r.opts.WatchPollInterval) * time.Millisecond
+	return nil, watcher.Run(ctx, pollInterval, onChange)
 }
 
 func (r *SkaffoldRunner) shouldWatch(artifact *v1alpha3.Artifact) bool {

pkg/skaffold/runner/runner_test.go

@@ -336,6 +336,9 @@ func TestDev(t *testing.T) {
 				Deployer:     test.deployer,
 				Tagger:       &tag.ChecksumTagger{},
 				watchFactory: test.watcherFactory,
+				opts: &config.SkaffoldOptions{
+					WatchPollInterval: 100,
+				},
 			}
 			_, err := runner.Dev(context.Background(), ioutil.Discard, nil)
 

pkg/skaffold/watch/watch.go

@@ -65,30 +65,45 @@ func (w *watchList) Run(ctx context.Context, pollInterval time.Duration, onChang
 	ticker := time.NewTicker(pollInterval)
 	defer ticker.Stop()
 
+	changedComponents := map[int]bool{}
+
 	for {
 		select {
 		case <-ctx.Done():
 			return nil
 		case <-ticker.C:
 			changed := 0
 
-			for _, component := range *w {
+			for i, component := range *w {
 				state, err := stat(component.deps)
 				if err != nil {
 					return errors.Wrap(err, "listing files")
 				}
 
 				if hasChanged(component.state, state) {
-					component.onChange()
+					changedComponents[i] = true
 					component.state = state
 					changed++
 				}
 			}
 
-			if changed > 0 {
+			// Rapid file changes that are more frequent than the poll interval would trigger
+			// multiple rebuilds.
+			// To prevent that, we debounce changes that happen too quickly
+			// by waiting for a full turn where nothing happens and trigger a rebuild for
+			// the accumulated changes.
+			if changed == 0 && len(changedComponents) > 0 {
+				for i, component := range *w {
+					if changedComponents[i] {
+						component.onChange()
+					}
+				}
+
 				if err := onChange(); err != nil {
 					return errors.Wrap(err, "calling final callback")
 				}
+
+				changedComponents = map[int]bool{}
 			}
 		}
 	}