Two QThreads and one static function cause havoc

[Jabber]

Surprisingly I have gotten the QThread example in the Qt documentation to actually work. (I only wish they had clearly indicated the use of "emit operate(QString("operate signal"));" to make it all dance).

To demonstrate that my two threads are working I have this code :

in the main app :
void BigFatApp::runController() {

controller = new Controller();
controller->doIt();

}

in the Controller and Worker classes :

void Controller::doIt() {

workerThread.start();

emit operate(QString("operate signal from doIt()"));  // make the workerThread dance

QThread::sleep(2.0);
std::cout << "Controller::doIt() after 2 sec" << std::endl;

QThread::sleep(2.0);
std::cout << "Controller::doIt() after 4 sec" << std::endl;

}

and :

*void Worker::doWork(const QString &parameter) {

/* ... here is the expensive or blocking operation ... */

std::cout << "Worker::doWork() " + parameter.toStdString() << std::cout;

QThread::sleep(2.0);
std::cout << "Worker::doWork after 2 sec" << std::endl;

QThread::sleep(2.0);
std::cout << "Worker::doWork after 4 sec" << std::endl;

QString result("result from Worker::doWork()");
emit resultReady(result);

}

However when I use K::show(std::string), a static function instead of std::cout, then my whole app locks up. Why?

And BTW, is QThread::sleep(1.0) the best way to introduce a time delay?

[jsulm]

Hello and welcome!

What is K::show(std::string) and what/how is it doing?

[mcosta]

HI and welcome to devnet,

And BTW, is QThread::sleep(1.0) the best way to introduce a time delay?

depends why you need a time delay. usually synchronization with delays is not a good idea.

[Jabber]

K.h

class K
    ...
static void show(std::string);
    ...

K.cpp

    ....
void K::showConsole(std::string s) {

	std::cout << s << std::endl;
}
    ...

[Jabber]

@mcosta
I'm not synchronising anything.
I'll be generating a variable takt mechanism
for controlling animation on a panel.

[Jakob]

@Jabber Which example? I know of a whole bunch of them

[topse]

OK... we know much to less, to help you here. Using a static function in general does not lock up anything. BTW why mix up std and Qt? Use qDebug()?

Tobias

[Jabber]

@topse said:

BTW why mix up std and Qt

with std::string I can concatenate with '+' and I've never used qDebug before. I'm not working in the Qt environment with this thing.
The example? http://doc.qt.io/qt-5/qthread.htmllink text

[topse]

std::cout << "Controller::doIt() after 2 sec" << std::endl;

==

qDebug() << "Controller::doIt() after 2 sec";

You can use + and << operators.

And sorry again: with the given Information I cant see what you are trying and so cant give more help :-/ Why you need a time delay in a worker thread?