Problem with QThread..

[endla.ravi]

hi..

I have a widget which is working fyn..

But in background an infinite loop should be there.When i put an infinite loop,the Widget becomes dark and finally crashes..

I think Threads can be used to solve this problem..(correct me if im wrong)

But i am unable to use QThread class ..for example if i have

mainwindow.h
@
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();

private:
Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H
@

mainwindow.cpp
@
#include "mainwindow.h"
#include "ui_mainwindow.h"

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

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

main.cpp
@
#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();

return a.exec();

}
@

And a MyThread class like this
@
class MyThread
{
public:void run();

};

void MyThread::run()
{
}
@

Now can anyone explain how to put the widget and while(1) {} loop in two different threads,so that both are running simultaneously...

Thanking u in advance

[edit: Code highlighted / Denis Kormalev]

[vcsala]

Can you please use '@' tags to make the code more readable?

[vcsala]

I am not sure you need threads, you can call processEvents from your infinite loop, which makes your GUI items responsive.

[DenisKormalev]

Please use @ tags for code. I edited your post, but in further posts please use it by yourself.

I don't see any usage of your MyThread class. And it should be inherited from QThread if you want to use threading.

[Smar]

Usually (mis)using threads causes gui going unresponsive...

Qt already have event loop, using own events and/or signal/slot system.

http://doc.qt.nokia.com/latest/signalsandslots.html
http://doc.qt.nokia.com/latest/eventsandfilters.html

[giesbert]

endla.ravi what do you want to do in your infinite loop? what is it needed or? Is it background processing (could be done in a thread) or shall it make event processing (is already done by return a.exec();)?

Please specify your needs a bit more.

[endla.ravi]

@above,

I am actually coding for a messenger

and my client should always be in listen mode,it should be listening for messages from other clients.
But when the client i listening for messages,the client become crashes after some time.

How could i handle this?

[giesbert]

You can look at the examples: "here":http://doc.qt.nokia.com/4.7/network-network-chat.html

[Wolf P.]

You have to subclass MyThread from QThread then define in its run method what you want to do in the background. Did you read the "basic thread example":http://doc.qt.nokia.com/4.7/qthread.html#details ?

[rugginoso]

Maybe in your case it's better to use the QThread::run() default implementation that runs a local (for thread) event loop.
You simply have to create your QWidget and your QThread, than use QObject::moveToThread() method and call the QThread::start() method.

References:
http://labs.qt.nokia.com/2010/06/17/youre-doing-it-wrong/
http://doc.qt.nokia.com/4.7/qthread.html#start
http://doc.qt.nokia.com/4.7/qobject.html#moveToThread

[dangelog]

[quote]and my client should always be in listen mode,it should be listening for messages from other clients.[/quote]

Please read my article here: http://developer.qt.nokia.com/wiki/ThreadsEventsQObjects . This seems to be the another case where threads are absolutely not needed (and indeed they just make your life a lot harder).

[rugginoso]

[quote author="peppe" date="1292837082"]
Please read my article here: http://developer.qt.nokia.com/wiki/ThreadsEventsQObjects . This seems to be the another case where threads are absolutely not needed (and indeed they just make your life a lot harder).[/quote]

Really good article :D

[Wolf P.]

[quote author="Il Rugginoso" date="1292836477"] http://labs.qt.nokia.com/2010/06/17/youre-doing-it-wrong/[/quote] Thanks for the tipp! I didn't know the concepts behind the QThread class...

[rugginoso]

[quote author="Wolf P." date="1292842687"][quote author="Il Rugginoso" date="1292836477"] http://labs.qt.nokia.com/2010/06/17/youre-doing-it-wrong/[/quote] Thanks for the tipp! I didn't know the concepts behind the QThread class...
[/quote]

You're welcome :D