Nested DirectConnection Signals are causing a segfault

Nested DirectConnection Signals are causing a segfault

By : Spencer Bass
Date : November 15 2020, 06:54 AM
hope this fix your issue I found a satisfying explanation here. Apparently, emitting a signal of type DirectConnection is equivalent to a direct function call. So the GUI is after all updated on a Worker thread when both signals are DirectConnect-ed. As mentioned on my other question, threads are not allowed to change the GUI. The issue is NOT with nesting DirectConnections per se.
code :

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Qt signals (QueuedConnection and DirectConnection)

Qt signals (QueuedConnection and DirectConnection)

By : user5835556
Date : March 29 2020, 07:55 AM
I wish did fix the issue. You won't see much of a difference unless you're working with objects having different thread affinities. Let's say you have QObjects A and B and they're both attached to different threads. A has a signal called somethingChanged() and B has a slot called handleChange().
If you use a direct connection
code :
connect( A, SIGNAL(somethingChanged()), B, SLOT(handleChange()), Qt::DirectConnection );
Getting segfault in qt5serialport.dll with PyQt and signals

Getting segfault in qt5serialport.dll with PyQt and signals

By : Samira Volpe
Date : March 29 2020, 07:55 AM
help you fix your problem You are facing this bug. This is a relative old issue and known. If we are lucky, it can be fixed for 5.2.1. Your workaround about not calling ser.close() in the readyRead signal handler looks reasonable.
Hope, this helps.
What is causing this segfault?

What is causing this segfault?

By : jrodriguez
Date : March 29 2020, 07:55 AM
wish of those help [This question has been edited heavily since yesterday. I'm updating to clarify the question.] , The problem is with:
code :
*p[i] = curr->ch;
(*p)[i] = curr->ch;
What is causing this segfault in Go?

What is causing this segfault in Go?

By : German Ayala
Date : March 29 2020, 07:55 AM
Hope that helps Background: Because Go's inbuilt JSON marshaller doesn't check for zero values when given the omitempty flag, we're trying using *time.Time rather than time.Time in structs that need to be marshalled cleanly to JSON. The problem with this is obviously we need to be very careful to always check it is not nil when using it. One thing we did notice was in a function that sets a creation time on the encompassing struct, when we checked the JSON in the database all of the times were exactly the same, down to the nanosecond. , In your loop you copy every Timekeeper value. Do this instead:
code :
for i := range t {
    now = time.Now()
    t[i].myTime = &now
Rapidly emitting signals in Qt causes a segfault

Rapidly emitting signals in Qt causes a segfault

By : Xiaocao Xiong
Date : March 29 2020, 07:55 AM
This might help you QML can not access another thread directly so if you connect an item to an object that is in another thread it causes problems like the one you observe. If you want to access another thread you must do it from the Python side, that is:
code :
Worker(another thread) --> Proxy(main Thread) --> QML
class Worker(QObject):

class Proxy(QObject):
    doSomethingDone = pyqtSignal()
    dataChanged = pyqtSignal(float, arguments=['data'])

if __name__ == '__main__':
    signal.signal(signal.SIGINT, signal.SIG_DFL)

    # Switch to the script directory so relative paths work correctly.

    app = QApplication(sys.argv)
    engine = QQmlApplicationEngine()

    workObject = Worker()
    workThread = QThread()
    proxy = Proxy()

    engine.rootContext().setContextProperty('worker', proxy)


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