perf: cache catchupped status

cmd/submit.go

@@ -118,6 +118,7 @@ func (s *submitter) shipFileRoutine(ctx context.Context, name string, sendQueue
 		return fmt.Errorf("tailing file: %w", err)
 	}
 
+	var catchUpped bool // cache
 	for {
 		select {
 		case err := <-errChan:
@@ -128,10 +129,14 @@ func (s *submitter) shipFileRoutine(ctx context.Context, name string, sendQueue
 				return nil
 			}
 
-			if line.EndOffset > startSize {
-				select {
-				case sigCatchupped <- struct{}{}:
-				default:
+			if !catchUpped {
+				catchUpped = line.EndOffset > startSize
+
+				if catchUpped {
+					select {
+					case sigCatchupped <- struct{}{}:
+					default:
+					}
 				}
 			}