1. The QThread::terminate function is highly discouraged because it can kill your thread at any execution point. You may find QThread::exit or QThread::quit(equivalent to QThread::exit(0)), which seem to stop a thread. But the official document only says they let the thread exits from the event loop, not saying they will stop the thread. If your thread is not being in an event loop, the functions have no effect.
2. If you subclass QThread and add your own slots, you may be surprised to learn that these slots will actually run on the main thread. This also means you cannot use the QThread object as the parent of a QObject instance that has affinity to the thread (i.e., one created within “run”).

• Qthread Slot
• Qthread Slot Quit Smoking
• Qthread Slots
• Qthread Yieldcurrentthread
• Qthread Slot Quits
• Qthread Lock

QThread

QThread Class, A QThread should be used much like a regular thread instance: prepare an object (QObject) class with all your desired functionality in it. Then Detailed Description. A QThread object manages one thread of control within the program. QThreads begin executing in run(). By default, run() starts the event loop by calling exec() and runs a Qt event loop inside the thread.

执行一个耗时的操作时，多线程是常用的选择，最常见的一个方式或许是继承QThread，然后实现其virtual void run函数，又或者使用高级类，比如QtConcurrent。总之，好像“回字的四种写法”，当然不同情况下，每种. This would be done by posting a suspend request into the queue and waiting until it is handled. Pretty much similar to QThread::quit + wait. Resume would signal the wait condition to wake the sleeping thread up to continue its execution. Let’s review the interface and implementation.

QThread Class, QThread::QThread ( unsigned int stackSize ). Constructs a new thread. The thread does not begin executing until start() is called. If stackSize is greater than zero, Detailed Description. The QThread class provides a platform-independent way to manage threads.. A QThread object manages one thread of control within the program. QThreads begin executing in run().

How To Really, Truly Use QThreads; The Full Explanation, the thread by calling exit() or quit(). In extreme cases, you may want to forcibly terminate() an executing thread. The rest of this article demonstrates one of these methods: QThread + a worker QObject. This method is intended for use cases which involve event-driven programming and signals + slots across threads. Usage with Worker class. The main thing in this example to keep in mind when using a QThread is that it's not a thread.

QEventLoop

QEventLoop Class, QEventLoop::QEventLoop(QObject *parent = nullptr). Constructs an event loop object with the given parent. [slot] void QEventLoop::quit(). Tells Detailed Description At any time, you can create a QEventLoop object and call exec () on it to start a local event loop. From within the event loop, calling exit () will force exec () to return.

List of All Members for QEventLoop, This is the complete list of members for QEventLoop, including inherited members. enum ProcessEventsFlag; flags ProcessEventsFlags · QEventLoop(​QObject *) The QEventLoop class provides a means of entering and leaving an event loop. At any time, you can create a QEventLoop object and call exec () on it to start a local event loop. From within the event loop, calling exit () will force exec () to return.

QEventLoop proper usage, I agree with @Mher-Didaryan - that the event loop started by following line of code loop.exec(); in the 2nd code snippet - will never exit. This is QEventLoop (QObject *parent=0) ~QEventLoop int: exec (ProcessEventsFlags flags=AllEvents) void: exit (int returnCode=0) bool: isRunning const : bool: processEvents (ProcessEventsFlags flags=AllEvents) void: processEvents (ProcessEventsFlags flags, int maximumTime) void: wakeUp ()

QThread deleteLater

QThread finished() connected to deletelater of a QObject, QThread will do a QCoreApplication::sendPostedEvents with a event type of QEvent::DeferredDelete after sending it's finished signal. in other I am sub-classing QThread and implementing a run method to perform some Task. I have few questions in cleanup of the sub-class object as below: I want to cleanup my sub-class (which derives from Qthread) in all the three cases: Thread has started and is i

QThread Class, The QThread class provides a platform-independent way to manage threads. connect(&workerThread, &QThread::finished, worker, &QObject::deleteLater); deleteLater() only means that the object will be deleted after all signal/slots int the current event loop (i.e. ThreadB) have been treated. So, if no other slots need ObjectX in ThreadB, it is equivalent to a plain delete. Whether you can delete the object or not and how it will be handled in ThreadA is up to your app logic.

QThread, I am sub-classing QThread and implementing a run method to perform some Task. I have few questions in cleanup of the sub-class object as If deleteLater() is called after the main event loop has stopped, the object will not be deleted. Since Qt 4.8, if deleteLater() is called on an object that lives in a thread with no running event loop, the object will be destroyed when the thread finishes.

QWaitCondition

QWaitCondition allows a thread to tell other threads that some sort of condition has been met. One or many threads can block waiting for a QWaitCondition to set a condition with wakeOne () or wakeAll (). Use wakeOne () to wake one randomly selected thread or wakeAll () to wake them all.

The QWaitCondition class provides a condition variable for synchronizing threads. QWaitCondition allows a thread to tell other threads that some sort of condition has been met. One or many threads can block waiting for a QWaitCondition to set a condition with wakeOne () or wakeAll ().

The QWaitCondition class provides a condition variable for synchronizing threads. QWaitCondition allows a thread to tell other threads that some sort of condition has been met. One or many threads can block waiting for a QWaitCondition to set a condition with wakeOne () or wakeAll ().

QTimer

QTimer Class, The QTimer class provides a high-level programming interface for timers. To use it, create a QTimer, connect its timeout() signal to the appropriate slots, and call The QTimer class provides a high-level programming interface for timers. To use it, create a QTimer, connect its timeout () signal to the appropriate slots, and call start (). From then on, it will emit the timeout () signal at constant intervals. Example for a one second (1000 millisecond) timer (from the Analog Clock example):

QTimer Class, The QTimer class provides a high-level programming interface for timers. To use it, create a QTimer, connect its timeout() signal to the appropriate slots, and call The QTimerclass provides a high-level programming interface for timers. To use it, create a QTimer, connect its timeout() signal to the appropriate slots, and call start(). From then on it will emit the timeout() signal at constant intervals. Example for a one second (1000 millisecond) timer (from the Analog Clockexample):

QTimer Class, It's good practice to give a parent to your QTimer to use Qt's memory management system. update() is a QWidget function - is that what you are Extending qTimer. If you’re interested in extending qTimer take a look at the plugins folder and the commands folder. A command is a class which provides a sub-parser and business logic for a given sub-command. See commands folder and command.py for details. A plugin represents a way of retrieving data from a remote source.

Qt thread

Threading Basics, QThread: Low-Level API with Optional Event Loops. QThread is the foundation of all thread control in Qt. Each QThread instance represents and controls one As mentioned, each program has one thread when it is started. This thread is called the 'main thread' (also known as the 'GUI thread' in Qt applications). The Qt GUI must run in this thread. All widgets and several related classes, for example QPixmap, don't work in secondary threads.

Multithreading Technologies in Qt, Starting Threads with QThread. A QThread instance represents a thread and provides the means to start() a thread, which will then execute the reimplementation Detailed Description A QThread object manages one thread of control within the program. QThreads begin executing in run (). By default, run () starts the event loop by calling exec () and runs a Qt event loop inside the thread.

Starting Threads with QThread, These threads share the process' resources but are able to execute independently. The threaded programming model provides developers with a useful As mentioned, each program has one thread when it is started. This thread is called the 'main thread' (also known as the 'GUI thread' in Qt applications). The Qt GUI must run in this thread. All widgets and several related classes, for example QPixmap, don't work in secondary threads.

Qt emit signal wait for response

Qt/C++ how to wait a slot when signal emitted, Then, when the other thread has done its work, it responds by emitting its own response-signal, causing the appropriate/connected slot-method It's also liable to result in deadlocks if you're not careful (e.g. if both threads decide to emit-and-wait at approximately the same time!) A better design would have the initiating method do the emit RequestIfNameExit and then return immediately, so that the initiating thread's event loop can continue running as usual during the operation. Then, when the other thread has done its work, it responds by emitting its own response-signal, causing the appropriate/connected slot-method in the

Synchronously waiting for a list of signals, But I always got 'timed out after ..s without signal' eventhough I emitted the signal​. Could that code work like this? Reply Quote 0. 1 Hi All! I need send some message by the local net, and than need wait to some answer or exit at the function by timeout, I try stop by forever loop, and there wait some signals, but no signal is comming (i think thats because i create this loop at the mai

wait until a signal is processed, I need to wait for a signal to be processed. According to the documentation, Qt::​BlockingQueuedConnection seems to be post topics, communicate privately with other members (PM), respond to polls, emit mysignal1(44);. Hi all, I am developing a multi-threaded app that emits signals processed in another threads. I need to wait for a signal to be processed. According to the documentation, Qt::BlockingQueuedConnection seems to be right for that case, but the following code doesn't work (connect returns false):

QThread event loop

Threads Events QObjects, Like QCoreApplication, QThread provides an exit(int) function and a quit() slot. An event loop in a thread makes it possible for the thread to use certain non-GUI​ QThread is the thread 'controller'. Its event loop doesn't block just because your QObject executes an infinite loop. Unless of course you're implementing that infinite loop in a QThread subclass. In your case, you don't have to do that.

Threads and QObjects, A loop always can be replaced with a function that is called multiple times (​although it's not always convenient). Create a slot and connect a Detailed Description A QThread object manages one thread of control within the program. QThreads begin executing in run (). By default, run () starts the event loop by calling exec () and runs a Qt event loop inside the thread.

QThread event loop and infinite work loop, QThread usage without an event loop. QThread p.15. Subclass QThread and override QThread::run(). Create an instance and start the new thread via Emitting signals itself doesn't require an event loop and is going to work regardless of you having a running event loop or not. @prex said in Proper way of creating an interface with a while-loop in a QThread :

QEventLoop example

QEventLoop Class, Constructs an event loop object with the given parent. [slot] void QEventLoop::​quit(). Tells the event loop to exit normally. Same as exit( C++ (Cpp) QEventLoop::exec - 30 examples found. These are the top rated real world C++ (Cpp) examples of QEventLoop::exec extracted from open source projects. You can rate examples to help us improve the quality of examples.

QEventLoop example, Hello, I was going through Qt help documents, in which I read about a class QEventLoop, which says that At any time, you can create a bool QEventLoop:: isRunning const. Returns true if the event loop is running; otherwise returns false. The event loop is considered running from the time when exec() is called until exit() is called. See also exec() and exit(). bool QEventLoop:: processEvents (QEventLoop::ProcessEventsFlags flags = AllEvents)

QEventLoop proper usage, Maybe you can use the below QEventLoop logic that would handle In your second example event loop will never quit, on the other hand in The QEventLoop class provides a means of entering and leaving an event loop. At any time, you can create a QEventLoop object and call exec () on it to start a local event loop. From within the event loop, calling exit () will force exec () to return.

Qt QThread example

QThread Class, In that example, the thread will exit after the run function has returned. There will not be any event loop running in the thread unless you call exec(). It is important to The rest of this article demonstrates one of these methods: QThread + a worker QObject. This method is intended for use cases which involve event-driven programming and signals + slots across threads. Usage with Worker class. The main thing in this example to keep in mind when using a QThread is that it's not a thread.

QThreads general usage, Usage with Worker class. The main thing in this example to keep in mind when using a QThread is that it's not a thread. It's a wrapper around a Threading is a collection of QML multithreading examples. Running the Example. To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example. Threaded ListModel. Threaded ListModel contains a ListView and a ListModel.

Qthread Slot

QThread Class, In that example, the thread will exit after the run function has returned. There will not be any event loop running in the thread unless you call exec(). It is important to If you don't call setObjectName(), the name given to your thread will be the class name of the runtime type of your thread object (for example, 'RenderThread' in the case of the Mandelbrot Example, as that is the name of the QThread subclass). Note that this is currently not available with release builds on Windows.

Qt event loop

QEventLoop Class, The main event loop receives events from the window system and dispatches these to the application widgets. Generally speaking, no user interaction can take​ The main event loop receives events from the window system and dispatches these to the application widgets. Generally speaking, no user interaction can take place before calling exec (). As a special case, modal widgets like QMessageBox can be used before calling exec (), because modal widgets use their own local event loop.

Threads Events QObjects, An event loop in a thread makes it possible for the thread to use certain non-GUI Qt classes that require the presence of an event loop (such as QTimer, QApplication exec starts the main event loop. It launches the GUI. It processes the signals and calls appropriate slots on receiving them. It waits until exit is called and returns the value which was set in exit.

Threads and QObjects, Now, when we say event loop, does it mean that there is some while loop running in the internal code of Qt, and in that while loop the method of The main event loop receives events from the window system and dispatches these to the application widgets. Generally speaking, no user interaction can take place before calling exec (). As a special case, modal widgets like QMessageBox can be used before calling exec (), because modal widgets use their own local event loop.

QThread join

This provides similar functionality to the POSIX pthread_join() function. This function was introduced in Qt 5.15. See also sleep() and terminate(). bool QThread:: wait (unsigned long time) This is an overloaded function. [static] void QThread:: yieldCurrentThread Yields execution of the current thread to another runnable thread, if any.

QThread will notifiy you via a signal when the thread is started() and finished(), or you can use isFinished() and isRunning() to query the state of the thread. You can stop the thread by calling exit() or quit() .

This provides similar functionality to the POSIX pthread_join() function. See also sleep() and terminate(). [static] void QThread:: yieldCurrentThread Yields execution of the current thread to another runnable thread, if any. Note that the operating system decides to which thread to switch.

More Articles

Creó un QThread en main (), es decir, el hilo principal. Se movió una clase trabajadora al nuevo hilo. El hilo ejecuta el método ‘StartThread’ de la clase de trabajo.

Hilo del trabajador:

Qthread Slot Quit Smoking

Main.cpp

Ahora, antes de que se complete el ‘StartThread’ y se salga el hilo con gracia, quiero detener el hilo desde el hilo principal. Usado,

1. subproceso-> salir () y esperó (subproceso-> esperar ()) en el subproceso principal.

2. thread-> quit () y esperó (thread-> wait ()) en el hilo principal.

3. exit () en el ‘StartThread’

Esperado: la ejecución del subproceso debe detenerse tan pronto como se llame a exit () / quit () desde el subproceso principal.

Real: en los tres casos, el hilo continúa ejecutándose, completa el método ‘StartThread’ y sale con gracia. Tan bueno como no se llamó a exit () / quit (). salida:

¿Es posible detener / desechar el hilo como está cuando lo requiere el hilo principal?

isInterruptionRequested solo devuelve true si ha llamado a QThread::requestInterruption , no aQThread::quit . Esto está documentado.

Si desea utilizar QThread::quit , el hilo debe girar un bucle de eventos, por lo que no debe derivarse de él; en lugar de hacer esto:

Para ejecutar el trabajador, créalo y muévalo a algo de su hilo. Para detener al trabajador, simplemente quit() su hilo antes de que el trabajador haya terminado.

En lugar de administrar la vida del hilo manualmente, es posible que desee utilizar un grupo de hilos en su lugar.

Una forma alternativa de finalizarlo sin ejecutar el bucle del evento principal habría sido:

Esta respuesta tiene un ejemplo completo de transmisión de múltiples trabajos a un grupo de subprocesos.

Parece que tienes muchos conceptos erróneos

De los documentos de Qt, tanto QThread::quit() como QThread::exit() :

Dile al bucle de eventos del hilo para salir

Eso significa que si el bucle de eventos del hilo no se está ejecutando (o bien no se ha llamado a QThread::exec() o si el bucle de eventos está ocupado ejecutando alguna función de locking pesado (como su StartThread )), el hilo no se cerrará hasta que el control vuelva. en el bucle de eventos. Creo que eso explica por qué quit() y exit() no funcionaron para usted como se esperaba.

También parece que QThread::requestInterruption() usando QThread::requestInterruption() de una manera incorrecta, de vuelta a los documentos de Qt :

Qthread Slots

Solicitar la interrupción del hilo. Esa solicitud es de asesoramiento y depende del código que se ejecuta en el hilo para decidir si y cómo debe actuar ante dicha solicitud. Esta función no detiene ningún bucle de eventos que se ejecute en el subproceso y no lo termina de ninguna manera.

así que esto realmente no hace nada con su hilo, solo hace que las llamadas subsiguientes a QThread::isInterruptionRequested() devuelvan true , de modo que cuando detecte que (dentro del hilo) debe realizar la limpieza y salir tan pronto como sea posible. es posible (de nuevo para que quit() funcione aquí, el bucle de eventos debería estar ejecutándose, por lo que debería regresar de su función StartThread aquí, para que el hilo vuelva a su ciclo de eventos nuevamente).

Ahora para responder a tu pregunta:

¿Es posible detener / desechar el hilo como está cuando lo requiere el hilo principal?

Para hacer eso, debe evitar las funciones de ejecución prolongada y asegurarse de regresar al bucle de eventos lo antes posible, de modo que quit() / exit() pueda funcionar. O realice la limpieza y regrese de la función actual tan pronto como detecte que isInterruptionRequested() está volviendo verdadero, de modo que las llamadas a quit() / exit() pueden funcionar después de eso.

Como lo señaló @kuba, puede elegir usar un grupo de subprocesos en lugar de administrar la vida de sus subprocesos manualmente.

Qthread Yieldcurrentthread

PD: no tiene que almacenar un puntero a su QThread dentro del Worker para usar isInterruptionRequested() . puede usar QThread::currentThread()->isInterruptionRequested() lugar de m_pCurrentThread->isInterruptionRequested() (lo mismo se aplica a su llamada de salida m_pCurrentThread->isInterruptionRequested() )

Qthread Slot Quits

Usted declaró e inicializó el count dentro del bucle while. Muévalo hacia afuera y dejará de reiniciarse a cero en cada iteración, y así saldrá a tiempo. No tengo claro por qué lo has declarado static , también.

Qthread Lock

Nota
Si pretende usar señales en cola y manejar eventos, asegúrese de llamar periódicamente a processEvents en el distribuidor de eventos del hilo dentro de su bucle while: