QThread/QObject and QTimer

[swiety]

I'm using QTimer in QThread( or QObject ) class :

class InfoThread: public QThreed
{
Q_OBJECT
...
 void run();
signals:
 void newInfoAvalible(  /* some data */  );
private slots:
 void update();
..
private:
 QTimer *p_timer;
};
 
InfoThread::Infothread( QObject *parent ) : QThread( parent )
{
 p_timer = new QTimer( this );
 connect(  p_timer, SIGNAL( timeout() ), this, SLOT( update() ) );
}
 
void InfoThread::run()
{
 p_timer->start( 1000 );
 exec(); // event loop for QTimer
}
 
void InfoThread::update()
{ 
 ...
 emit newInfoAvalible( /* some data */ );
}

class InfoThread: public QThreed
{
Q_OBJECT
...
 void run();
signals:
 void newInfoAvalible(  /* some data */  );
private slots:
 void update();
..
private:
 QTimer *p_timer;
};

InfoThread::Infothread( QObject *parent ) : QThread( parent )
{
 p_timer = new QTimer( this );
 connect(  p_timer, SIGNAL( timeout() ), this, SLOT( update() ) );
}

void InfoThread::run()
{
 p_timer->start( 1000 );
 exec(); // event loop for QTimer
}

void InfoThread::update()
{ 
 ...
 emit newInfoAvalible( /* some data */ );
}

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For me code is good, but signal newInfoAvalible( /* some data */ ) causes apps to crash. Wher's the problem?

[seveninches]

Is newInfoAvalible() connected to a slot in another QThread?
If so, does the /*some data*/ contain pointers to something which are invalid after you leave this function? If so, this is expected, as signals between threads use "queued connections".

[jpn]

The QTimer object must be created in InfoThread::run() without a parent (preferably on the stack since QThread::exec() blocks) and the connection must be forced as direct

connect(  &timer, SIGNAL( timeout() ), this, SLOT( update() ), Qt::DirectConnection );

connect(  &timer, SIGNAL( timeout() ), this, SLOT( update() ), Qt::DirectConnection );

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because QThread itself lives in different thread than what's being executed in QThread::run().