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Stopping a thread that tries to acquire a QSystemSemaphore



  • Hi there,

    I'm using QSystemSemaphore for interprocess-communication. Two processes shall acquire the systemsemaphore by turns.

    The flow of my application is as follows:
    -ProcessA creates the QSystemSemaphore with key "x" and acquires it.
    -ProcessB has a thread that creates the QSystemSemaphore with key "x". Since I'm using Windows, the QSystemSemaphore is not created but the already existing one is used.
    -the thread of ProcessB tries to acquire the QSystemSemaphore and blocks, until ProcessA releases the QSystemSemaphore.
    -ProcessA tries to acquire the QSystemSemaphore and blocks, until the thread of ProcessB releases the QSystemSemaphore.
    -the thread of ProcessB tries to acquire the QSystemSemaphore and blocks, until ProcessA releases the QSystemSemaphore.
    -...

    Everything works fine, but when I want to stop the thread, my application crashes. I can't figure out a way, to stop the thread from running, since the acquire-method blocks.

    The relevant parts of my code are:

    @
    //the method 'stopWorking' should stop the sharedMemoryLayer from grasping the QSystemSemaphore
    void Application::stopWorking() {

    if (thread->isRunning()) { //the sharedMemoryLayer runs within the thread 'thread'. I moved it there using 'moveToThread'
    thread->quit();
    thread->wait();
    }
    }
    @

    My question is:
    Is it possbible to stop that thread? If yes, how?
    Completly deleting it and creating a new object is absolutly acceptable, but even this crashed my application.

    Greetings and thanks in advance
    Christian


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