Remove data race in the runner length function

Makefile

@@ -66,7 +66,7 @@ test: deps ## Run unit tests
 
 .PHONY: race
 race: deps ## Run data race detector
-	@go test -race -short $(UNIT_TESTS)
+	@go test -race -count=1 -short $(UNIT_TESTS)
 
 .PHONY: coverage
 coverage: deps ## Generate code coverage report

runner/storage.go

@@ -70,5 +70,7 @@ func (s *localRunnerStorage) Sample() (Runner, bool) {
 }
 
 func (s *localRunnerStorage) Length() int {
+	s.RLock()
+	defer s.RUnlock()
 	return len(s.runners)
 }