textprogress bar in parfor

Hey, this used to work in Matlab 2019b and before, to show a progressbar in a parfor loop:

%% par pool
[~, output] = system('free -b | awk ''/Mem/{print $2}''');
total_memory = str2double(output);

myCluster = min(ceil(total_memory / 1024^2 / 2 / 1000), round(maxNumCompThreads));
if isempty(gcp('nocreate'))
    pool=parpool(myCluster,'IdleTimeout', 604800);%1 week
end
nsim = 50

%% -----------------------------------
global P;
P = 1;
DataQueue = parallel.pool.DataQueue;
textprogressbar('start: ');
afterEach(DataQueue, @(ss) textprogressbar(P/nsim*100));
afterEach(DataQueue, @updateP);
parfor i = 1:nsim
    send(DataQueue,i);
    %someprocess
    pause(0.1)
end
textprogressbar(' done')

%------------------------------------
function updateP(~)
    global P; %#ok<*GVMIS>
    P = P+1;

Now, I updated to 2024a Update 4 (24.1.0.2628055). And even though the parloop runs just fine, the progressbar is never updated.

Here's the code of textprogressbar I took somewhere from around here:

function textprogressbar(c)
% This function creates a text progress bar. It should be called with a 
% STRING argument to initialize and terminate. Otherwise the number correspoding 
% to progress in % should be supplied.
% INPUTS:   C   Either: Text string to initialize or terminate 
%                       Percentage number to show progress 
% OUTPUTS:  N/A
% Example:  Please refer to demo_textprogressbar.m

% Author: Paul Proteus (e-mail: proteus.paul (at) yahoo (dot) com)
% Version: 1.0
% Changes tracker:  29.06.2010  - First version

% Inspired by: http://blogs.mathworks.com/loren/2007/08/01/monitoring-progress-of-a-calculation/

%% Initialization
persistent strCR;           %   Carriage return pesistent variable

% Vizualization parameters
strPercentageLength = 6;   %   Length of percentage string (must be >5)
strDotsMaximum      = 10;   %   The total number of dots in a progress bar

%% Main 

if isempty(strCR) && ~ischar(c),
    % Progress bar must be initialized with a string
    error('The text progress must be initialized with a string');
elseif isempty(strCR) && ischar(c),
    % Progress bar - initialization
    % fprintf('%s',c);
    tcprintf('green',c);
    strCR = -1;
elseif ~isempty(strCR) && ischar(c),
    % Progress bar  - termination
    strCR = [];  
    % fprintf([c '\n']);
    tcprintf('red',[c '\n']);
elseif isnumeric(c)
    % Progress bar - normal progress
    c = floor(c);
    percentageOut = [num2str(c) '%%'];
    percentageOut = [percentageOut repmat(' ',1,strPercentageLength-length(percentageOut)-1)];
    nDots = floor(c/100*strDotsMaximum);
    dotOut = ['[' repmat('.',1,nDots) repmat(' ',1,strDotsMaximum-nDots) ']'];
    strOut = [percentageOut dotOut];
    
    % Print it on the screen BAR!!!!
    if strCR == -1,
        % Don't do carriage return during first run
        fprintf(strOut);
        % tcprintf('yellow',strOut);
    else
        % Do it during all the other runs
        fprintf([strCR strOut]);
        % tcprintf('yellow',[strCR strOut]);
    end
    
    % Update carriage return
    strCR = repmat('\b',1,length(strOut)-1);
    
else
    % Any other unexpected input
    error('Unsupported argument type');
end
%%---------------------------------------------------
    function tcprintf(style, fmatString, varargin)
        % Uses ANSI escape codes to print colored output when using MATLAB
        % from a terminal. If not running in a terminal, or if called by MATLAB's
        % datatipinfo function, tcprintf reverts to standard printf. The latter is
        % desirable if tcprintf is used within an object's disp() method to avoid
        % seeing the ANSI characters here.
        %
        % The first argument is an style description that consists of space-separated
        % words. These words may include: 
        %
        % one of the following colors:
        %   black, red, green, yellow, blue, purple, cyan, darkGray, lightGray, white
        %
        % one of the following background colors:
        %   onBlack, onRed, onGreen, onYellow, onBlue, onPurple, onCyan, onWhite
        %
        % and any of the following modifiers:
        %   bright : use the bright (or bold) form of the color, not applicable for
        %       black, darkGray, lightGray, or white
        %   underline : draw an underline under each character
        %   blink : This is a mistake. Please don't use this ever.
        %
        % Example:
        %   tcprintf('lightGray onRed underline', 'Message: %20s\n', msg);
        %
        % Author: Dan O'Shea dan at djoshea.com (c) 2012
        %
        % Released under the open source BSD license 
        %   opensource.org/licenses/bsd-license.php
        
        if nargin < 2 || ~ischar(style) || ~ischar(fmatString)
            error('Usage: tcprintf(style, fmatString, ...)');
        end
        
        % determine if we're using 
        usingTerminal = ~usejava('desktop');
        
        % determine if datatipinfo is higher on the stack. If tcprintf
        % is used within an object's disp() method, we don't want to
        % use color in the hover datatip or all you'll see are ANSI codes.
        stack = dbstack;
        inDataTip = ismember('datatipinfo', {stack.name});
        
        if ~usingTerminal || inDataTip
            % print the message without color and return
            fprintf(fmatString, varargin{:});
            return;
        end
        
        bright = 1;
        [colorName backColorName bright underline blink] = parseStyle(style);
        colorCodes = getColorCode(colorName, bright);
        backColorCodes = getBackColorCode(backColorName);
        
        codes = [colorCodes; backColorCodes];
        
        if underline
            codes = [codes; 4];
        end
        
        if blink
            codes = [codes; 5];
        end
        
        codeStr = strjoin(codes, ';');
        
        % evaluate the printf style message
        contents = sprintf(fmatString, varargin{:});
        
        % if the message ends with a newline, we should turn off
        % formatting before the newline to avoid issues with 
        % background colors
        if ~isempty(contents) && contents(end) == char(10)
            contents = contents(1:end-1);
            endOfLine = char(10);
        else
            endOfLine = '';
        end
        
        str = ['\033[' codeStr 'm' contents '\033[0m' endOfLine];
        fprintf(str);
    end

    function [colorName backColorName bright underline blink] = parseStyle(style)
        defaultColor = 'white';
        defaultBackColor = 'onDefault';
        
        tokens = regexp(style, '(?<value>\S+)[\s]?', 'names');
        
        values = {tokens.value};
        
        if ismember('bright', values)
            bright = true;
        else
            bright = false;
        end
        
        if ismember('underline', values)
            underline = true;
        else
            underline = false;
        end
        
        if ismember('blink', values)
            blink = true;
        else
            blink = false;
        end
        
        % find foreground color
        colorList = {'black', 'darkGray', 'lightGray', 'red', 'green', 'yellow', ...
            'blue', 'purple', 'cyan', 'lightGray', 'white', 'default'};
        idxColor = find(ismember(colorList, values), 1);
        if ~isempty(idxColor)
            colorName = colorList{idxColor}; 
        else
            colorName = defaultColor;
        end
        
        % find background color
        backColorList = {'onBlack', 'onRed', 'onGreen', 'onYellow', 'onBlue', ...
            'onPurple', 'onCyan', 'onWhite', 'onDefault'};
        idxBackColor = find(ismember(backColorList, values), 1);
        if ~isempty(idxBackColor)
            backColorName = backColorList{idxBackColor}; 
        else
            backColorName = defaultBackColor;
        end
        
    end

    function colorCodes = getColorCode(colorName, bright)
        
        switch colorName
            case 'black'
                code = 30;
                bright = 0;
            case 'darkGray';
                code = 30;
                bright = 1;
            case 'red'
                code = 31;
            case 'green'
                code = 32;
            case 'yellow'
                code = 33;
            case 'blue'
                code = 34;
            case 'purple'
                code = 35;
            case 'cyan'
                code = 36;
            case 'lightGray'
                code = 37;
                bright = 0;
            case 'white'
                code = 37;
                bright = 1;
            case 'default'
                code = 39;
        end
        
        if bright
            colorCodes = [1; code];
        else
            colorCodes = [code];
        end
        
    end

    function colorCodes = getBackColorCode(colorName)
        
        switch colorName
            case 'onBlack'
                code = 40;
            case 'onRed'
                code = 41;
            case 'onGreen'
                code = 42;
            case 'onYellow'
                code = 43;
            case 'onBlue'
                code = 44;
            case 'onPurple'
                code = 45;
            case 'onCyan'
                code = 46;
            case 'onWhite'
                code = 47;
            case 'onDefault'
                code = 49;
        end
        
        colorCodes = code;
    end

    function str = strjoin(strCell, join)
        % str = strjoin(strCell, join)
        % creates a string by concatenating the elements of strCell, separated by the string
        % in join (default = ', ')
        %
        % e.g. strCell = {'a','b'}, join = ', ' [ default ] --> str = 'a, b'
        
        if nargin < 2
            join = ', ';
        end
        
        if isempty(strCell)
            str = '';
        else
            if isnumeric(strCell) || islogical(strCell)
                % convert numeric vectors to strings
                strCell = arrayfun(@num2str, strCell, 'UniformOutput', false);
            end
            
            str = cellfun(@(str) [str join], strCell, ...
                'UniformOutput', false);
            str = [str{:}]; 
            str = str(1:end-length(join));
        end
    end

[Walter Roberson]

afterEach(DataQueue, @(ss) textprogressbar(P/nsim*100));
afterEach(DataQueue, @updateP);

I wonder whether the @updateP is replacing the @(ss) etc ?

If so, that would be contrary to the documentation of afterEach:

"You can specify multiple different functions to call, because each call to afterEach creates a new listener on the queue. If you want to specify another function, call afterEach again."

[Luis]

how to specify multiple funtions in a single afterEach?

And I added the updateP funtion to the code

[Walter Roberson]

Calling afterEach multiple times is correct.

But on the off-chance that the last one is replacing the first, try the debugging move of reversing the order of the two calls and see whether that makes a difference in the results.

[Luis]

hey, both gave the same results.

Answer 1

[Madheswaran]

Hello Luis,

As you described, the ‘parfor’ loop executes correctly, but the progress bar does not update as expected. I executed your code in MATLAB R2019b and was unable to replicate the issue you described. I noticed you're using multiple 'afterEach' functions, which means multiple functions run after each piece of data is received by the ‘DataQueue’.

With my current understanding, the problem arises due to the order of execution of 'updateP' function and 'textprogressbar' function, as the 'updateP' function is being prioritized. You can confirm this by inserting 'disp' statements within both functions to track their execution.

If your goal is to show the progress bar using the ‘textprogressbar’ function in the ‘parfor’ loop, these changes would help you out:

% ... existing code

function updateProgressBar(nsim)
global P;
P = P + 1;
textprogressbar(P/nsim*100);
end

afterEach(DataQueue, @(ss) updateProgressBar(nsim));

textprogressbar('start: ');
parfor i = 1:nsim
    send(DataQueue, i);
    %someprocess
    pause(0.2);
end
textprogressbar(' done');

% ... existing code

In this updated code, I included the ‘textprogressbar’ function inside your ‘updateP’ function and used just one ‘afterEach’ function to call ‘updateProgressBar’. This way, we avoid issues with the order of execution of the callback functions.

I hope this helps!

[Luis]

thanks a lot!!