Cannot break the while loop due to imagedatastore

Hi all,

I have build a simple app (appdesigner) which looks for new images in specific network storage and processess the data.

Since I am doing the searching for new files in a while loop I wand to be able to break when a stop button is pushed. The code looks following:

The issue I have is that the code works well till I add the dir_content2 in a while loop. Since then I cannot close the app other way than ctrl+C.

It looks that using imagaDatastore object to check the directory content is the issue. Any ideas what is happening?

EDIT: I found that when I use pause(0.1) at the end of the loop, it is possible to do do the break.

    properties (Access = public)
        stop_sim = false;
        modelName;
        model;
        net;
        anchors;
        classNames;
        executionEnvironment;
        folder;
        dir_content;
        filenames;
        current_files;
        DB_address;
        DB_port;
        tablename;
        conn;
        StopValue;
    end
    methods (Access = private)
        function stopSimulation(app)
            app.stop_sim = true;
            msgbox('Application stopped');
            app.delete;
        end

        function startSimulation(app)
            i = 0;
            ExitCount = 1;
            %             i=0;
            counter = 1;
            while i<=1000000 && app.stop_sim == false
                i = i +1;
                counter = 1;
                counter = counter+1;
                dir_content2 = imageDatastore(app.folder, "IncludeSubfolders",true);
                
                %% processing parth goes here 
            end
        end
    end

    % Callbacks that handle component events
    methods (Access = private)

        % Button pushed function: StartButton
        function StartButtonPushed(app, event)

            app.status.Value = ('loading data');
            app.StopValue = 0;
            app.ImageAxes.Visible = 'off';
            app.ImageAxes.Colormap = gray(256);
            axis(app.ImageAxes, 'image');
            %% YOLO model

            %% configuration

            %#exclude appconfig.txt
            Config = fileread('appconfig.txt')
            config = split(Config);
            app.status.Value = ('waiting for new files');
            app.folder = config{3};
            app.DB_address = string(config{6});
            DBport = config{9};
            app.DB_port = str2double(DBport);
            app.dir_content = imageDatastore(app.folder,"IncludeSubfolders",true);

            app.filenames = app.dir_content.Files;
            app.current_files = app.filenames;
            %% database;
            startSimulation(app)
        end

        % Button pushed function: StopButton
        function StopButtonPushed(app, event)
            stopSimulation(app)
        end
    end

    % Component initialization
    methods (Access = private)


    % App creation and deletion
    methods (Access = public)

        % Construct app
        function app = IMAD_app_07

            % Create UIFigure and components
            createComponents(app)

            % Register the app with App Designer
            registerApp(app, app.UIFigure)

            if nargout == 0
                clear app
            end
        end

        % Code that executes before app deletion
        function delete(app)

            % Delete UIFigure when app is deleted
            delete(app.UIFigure)
        end
    end
end

Answer 1

[Adam Drake]

What is the purpose of your while loop? I would suggest using a for loop instead of a counter OR flag app.stop_sim programatically whenever you finish processing. If you store all of the images in your directory, there's no need to do it again, much less 10000000 times.

% Example
imds = imageDatastore(app.folder, "IncludeSubfolders",true);

for i = 1:length(imds)
    img = readimage(imds,i)
end

[Marcin Kowalski]

The purpose of the while loop it to wait for new file to appear. And since they appear in variant moments the loop should run non-stop. Also, I cannot wait to process "all at once" but each image should be analyzed when appears.

Also, the condition i<=1000000 is due to high RAM consumption after couple of hours analysis. It does not neceserilly mean that the app processed many images, but the RAM consumption increases every minute, with no real reason. The only idea I found it to restart the app after pre-defined numer of rounds.

[Adam Drake]

Your RAM consumption is because you're reading every image in your directory 1000000 times.

1. An image is added to your directory.
2. You store it.
3. You do processing.

Now you loop back regardless of if another image was produced and read it again. When another image is added to the directory, you're now storing 2 images everytime. This is not efficient coding. You need to have a function run processing whenever an image is added to the directory and only store that one image. You need to look at appending to the imageDatastore object when a new image is added to the directory.

To detect when a new image is added to the directory SEE https://www.mathworks.com/matlabcentral/answers/18232-detect-new-file-in-a-directory

If I have answered your question, please Accept. Thanks!

[Marcin Kowalski]

Thank you answer.

I replaced imageDatastore with dir and looks more effective in terms of RAM consumption, for sure. To break, pause was needed.