Implementation of timer makes the program to continuously slow down

[Yorma]

The main idea is to have time shown on Qtable (is there a better class for it?) on main widget. At first the time is updated correctly every second, but after ~10 seconds the time is updated only every 2, 3, etc seconds. Now I think for some reason something makes the program slow down, and for that the clock is updated more infrequent. There may be some loop that i cant notice that continues to eat up the resources more and more after each update:

class test : public QObject
{
Q_OBJECT
public:
   test(QWidget *qwi,QLabel *qlb);
 
public slots:
   void	upd();
 
private:
  QWidget *qw;
  QLabel *ql;
};
 
test::test(QWidget *qwi, QLabel *qlb)
{
   qw = qwi;
   ql = qlb;
}
 
void test::upd()
{
   QTimer *timer = new QTimer();
   connect(timer,SIGNAL(timeout()),this,SLOT(upd())); 
   timer->start(1000);
   QTime time = QTime::currentTime();
   QString str = "<font color='green'>";
   str.append(time.toString("hh:mm:ss"));
   str.append("</font>");
   ql->setText(str);
   qw->update();
}
 
 
int main (int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    QWidget window;
 
    window.resize(1024, 768);
    QLabel *timeLabel = new QLabel(&window);
    timeLabel->setFrameStyle(QFrame::NoFrame | QFrame::Plain);
    timeLabel->setFont(QFont("Times", 20, QFont::Bold));
    timeLabel->setAlignment(Qt::AlignBottom | Qt::AlignRight);
    QString str = "<font color='green'>";
    QTime time = QTime::currentTime();
    str.append(time.toString("hh:mm:ss"));
    str.append("</font>");
    timeLabel->setText(str);
 
    QPalette palette(QApplication::palette());
    window.setParent(0,Qt::FramelessWindowHint);
    palette.setColor(QPalette::Background, QColor("Black"));
    QPushButton quit("Quit", &window);
    quit.setFont(QFont("Times", 18, QFont::Bold));
    palette.setColor(QPalette::Button, QColor("Blue"));
    window.setPalette(palette);
    quit.setPalette(palette);
    quit.setGeometry(974, 0, 50, 20);
    QObject::connect(&quit, SIGNAL(clicked()), &app, SLOT(quit()));
 
 
    window.show();
 
    test *t = new test(&window,timeLabel);
    t->upd();
    return app.exec();
}
 
#include "main.moc"

class test : public QObject
{
Q_OBJECT
public:
   test(QWidget *qwi,QLabel *qlb);

public slots:
   void	upd();

private:
  QWidget *qw;
  QLabel *ql;
};

test::test(QWidget *qwi, QLabel *qlb)
{
   qw = qwi;
   ql = qlb;
}

void test::upd()
{
   QTimer *timer = new QTimer();
   connect(timer,SIGNAL(timeout()),this,SLOT(upd())); 
   timer->start(1000);
   QTime time = QTime::currentTime();
   QString str = "<font color='green'>";
   str.append(time.toString("hh:mm:ss"));
   str.append("</font>");
   ql->setText(str);
   qw->update();
}


int main (int argc, char *argv[])
{
    QApplication app(argc, argv);

    QWidget window;
   
    window.resize(1024, 768);
    QLabel *timeLabel = new QLabel(&window);
    timeLabel->setFrameStyle(QFrame::NoFrame | QFrame::Plain);
    timeLabel->setFont(QFont("Times", 20, QFont::Bold));
    timeLabel->setAlignment(Qt::AlignBottom | Qt::AlignRight);
    QString str = "<font color='green'>";
    QTime time = QTime::currentTime();
    str.append(time.toString("hh:mm:ss"));
    str.append("</font>");
    timeLabel->setText(str);
    
    QPalette palette(QApplication::palette());
    window.setParent(0,Qt::FramelessWindowHint);
    palette.setColor(QPalette::Background, QColor("Black"));
    QPushButton quit("Quit", &window);
    quit.setFont(QFont("Times", 18, QFont::Bold));
    palette.setColor(QPalette::Button, QColor("Blue"));
    window.setPalette(palette);
    quit.setPalette(palette);
    quit.setGeometry(974, 0, 50, 20);
    QObject::connect(&quit, SIGNAL(clicked()), &app, SLOT(quit()));


    window.show();
    
    test *t = new test(&window,timeLabel);
    t->upd();
    return app.exec();
}

#include "main.moc"

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[jacek]

Now I think for some reason something makes the program slow down, and for that the clock is updated more infrequent. There may be some loop that i cant notice that continues to eat up the resources more and more after each update:

void test::upd()
{
   QTimer *timer = new QTimer();
   connect(timer,SIGNAL(timeout()),this,SLOT(upd())); 
   timer->start(1000);
   // ...
}

void test::upd()
{
   QTimer *timer = new QTimer();
   connect(timer,SIGNAL(timeout()),this,SLOT(upd())); 
   timer->start(1000);
   // ...
}

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Every time you invoke test::upd() you create a new timer, so after first second your will have 2 timers, after second one --- 4, then 8, 16, 32, ..., and after a minute you will have about 10^19 timers.

Create that timer only once.