Perform a cleaner exit for resource preview, fixes #24206

editor/editor_node.cpp

@@ -494,7 +494,7 @@ void EditorNode::_fs_changed() {
 			}
 		}
 
-		get_tree()->quit();
+		_exit_editor();
 	}
 }
 
@@ -1120,7 +1120,7 @@ void EditorNode::save_all_scenes_and_restart() {
 		to_reopen = get_tree()->get_edited_scene_root()->get_filename();
 	}
 
-	get_tree()->quit();
+	_exit_editor();
 	String exec = OS::get_singleton()->get_executable_path();
 
 	List<String> args;
@@ -2356,6 +2356,12 @@ int EditorNode::_next_unsaved_scene(bool p_valid_filename, int p_start) {
 	return -1;
 }
 
+void EditorNode::_exit_editor() {
+	exiting = true;
+	resource_preview->stop(); //stop early to avoid crashes
+	get_tree()->quit();
+}
+
 void EditorNode::_discard_changes(const String &p_str) {
 
 	switch (current_option) {
@@ -2383,14 +2389,13 @@ void EditorNode::_discard_changes(const String &p_str) {
 		case FILE_QUIT: {
 
 			_menu_option_confirm(RUN_STOP, true);
-			exiting = true;
+			_exit_editor();
-			get_tree()->quit();
+
 		} break;
 		case RUN_PROJECT_MANAGER: {
 
 			_menu_option_confirm(RUN_STOP, true);
-			exiting = true;
+			_exit_editor();
-			get_tree()->quit();
 			String exec = OS::get_singleton()->get_executable_path();
 
 			List<String> args;

editor/editor_node.h

@@ -470,6 +470,8 @@ private:
 	void _dropped_files(const Vector<String> &p_files, int p_screen);
 	String _recent_scene;
 
+	void _exit_editor();
+
 	bool convert_old;
 
 	void _unhandled_input(const Ref<InputEvent> &p_event);

editor/editor_resource_preview.cpp

@@ -416,6 +416,16 @@ void EditorResourcePreview::check_for_invalidation(const String &p_path) {
 	}
 }
 
+void EditorResourcePreview::stop() {
+	if (thread) {
+		exit = true;
+		preview_sem->post();
+		Thread::wait_to_finish(thread);
+		memdelete(thread);
+		thread = NULL;
+	}
+}
+
 EditorResourcePreview::EditorResourcePreview() {
 	singleton = this;
 	preview_mutex = Mutex::create();
@@ -428,10 +438,7 @@ EditorResourcePreview::EditorResourcePreview() {
 
 EditorResourcePreview::~EditorResourcePreview() {
 
-	exit = true;
+	stop();
-	preview_sem->post();
-	Thread::wait_to_finish(thread);
-	memdelete(thread);
 	memdelete(preview_mutex);
 	memdelete(preview_sem);
 }

editor/editor_resource_preview.h

@@ -126,6 +126,8 @@ public:
 	void remove_preview_generator(const Ref<EditorResourcePreviewGenerator> &p_generator);
 	void check_for_invalidation(const String &p_path);
 
+	void stop();
+
 	EditorResourcePreview();
 	~EditorResourcePreview();
 };