WI see memory leakage when a trigger a signal and empty slot is executed in qt?

[stackprogramer]

Hi, I created a simple application and this application has only a button and a LineEdit...When I click on the start button I see that application memory increases step by step in case I clicked on the button...Is this memory leakage?
Why do a simple signal and empty slot cause this problem? see screenshots...

void MainWindow::on_pushButtonStart_clicked()
{
 if(ui->lineEditFileSelected->text().isEmpty())
     {
       
        return;
     }
}

[JonB]

@stackprogramer
What is the usage after you have pressed it 100 times?

[stackprogramer]

Gradually used memory volume is increased... even for 100 times... and ...so on

[stackprogramer]

There is no One that can help me for understanding this strange problem?

[Christian Ehrlicher]

Provide a minimal, compilable example - your code snippet does not cause a leak.

[stackprogramer]

@Christian-Ehrlicher I attached a minimal application.
You should compile it and only click on the tool button to select a file or empty one...
For me, my memory increased every time I did it.

You can dowload it from below link
https://www.mediafire.com/file/ji6o7npfvjgwyyi/Qt-Test.zip/file

[Christian Ehrlicher]

Your example does not leak anything. Use a proper memory leak checker like e.g. valgrind or similar. ps ux or the windows task manager are not sufficient to detect memory leaks.

[stackprogramer]

@Christian-Ehrlicher said in WI see memory leakage when a trigger a signal and empty slot is executed in qt?:

valgrind

So after some time that I use my program after 10000 clicks.... what will happen to my software? I think that for a 4G RAM, it will be crashed??
on your system memory is not increased by clicking on the tool button?

[mpergand]

@stackprogramer said in WI see memory leakage when a trigger a signal and empty slot is executed in qt?:

So after some time that I use my program after 10000 clicks.... what will happen

Have a try with this:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QTimer>


 string selectedFilePath;
 string selectedFileName;

QFileDialog* fileNameDialog;


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    fileNameDialog=new QFileDialog;

    auto loopTimer=new QTimer;
    loopTimer->start(1000);

    connect(loopTimer,&QTimer::timeout,this,[this]()
    {
        QTimer::singleShot(500,this,[]() {

            fileNameDialog->close();
        });

         ui->toolButton->click();
    });

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_toolButton_clicked()
{
    fileNameDialog->setFileMode(QFileDialog::AnyFile);
//    QString fileName = fileNameDialog->getOpenFileName(
//        this, tr("Open File"), QDir::currentPath(), tr("Format (*.html *.iq  *.txt *.h)"));
//    ui->lineEditFileSelected->setText(fileName);
    fileNameDialog->open();

    selectedFilePath = ui->lineEditFileSelected->text().toStdString();
    selectedFileName = selectedFilePath;
}

On KDE mem usage stabilizes around 38Mb.

[Christian Ehrlicher]

@stackprogramer said in WI see memory leakage when a trigger a signal and empty slot is executed in qt?:

So after some time that I use my program after 10000 clicks.... what will happen to my software? I think that for a 4G RAM, it will be crashed??

Since there is no memleak in your example code it will not crash due to out of memory problems.

[stackprogramer]

@mpergand But I can not comment on the getOpenFileName, It is not solving the problem...

@Christian-Ehrlicher Thanks very much. According to your talking so I concluded operating system should manage and free up the memory...