logo
down
shadow

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 :


Share : facebook icon twitter icon
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.
    os.chdir(os.path.dirname(os.path.abspath(__file__)))

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

    workObject = Worker()
    workThread = QThread()
    proxy = Proxy()
    workObject.doSomethingDone.connect(proxy.doSomethingDone)
    workObject.dataChanged.connect(proxy.dataChanged)

    engine.rootContext().setContextProperty('worker', proxy)
    engine.load('qml/StartPage.qml')

    workThread.started.connect(workObject.do_something)
    workObject.moveToThread(workThread)
    workThread.start()

    sys.exit(app.exec_())
Related Posts Related Posts :
  • Vector of pointers: some clarification needed
  • scaling a bitmap without losing quality
  • How to evaluate a function directly?
  • QNetworkAccessManager: How to change post data at createRequest function
  • Returning std::move of a local variable
  • Is there a fast linear SVM library with a good C++ interface?
  • What is the purpose of name mangling in C++?
  • C++ Why the void function is not working eventhough I called it?
  • How the pointer and the pointer's adress can share the same memory adress?
  • error C2220: warning treated as error - no 'object' file generated
  • exception of strcpy function in c++ console program
  • How to access USB barcode scanner data directly from USB port using C/C++ without driver
  • Under which circumstances will std::vector.clear() call a destructor?
  • Template partial specialisation and dependent names
  • best way to share data between c codes
  • C++ ignores if statement conditions
  • How to set the argv[ ] to be case-insensitive in a Win32 Console Application?
  • How to fix error "clang: error: linker (via gcc) command failed with exit code 1 (use -v to see invocation)"?
  • C++ How do I print a .txt file verbatim?
  • Creating two dimensional array of class
  • How do I correctly use COMMTIMEOUTS with OVERLAPPED IO mode reading from a Serial port
  • An assert macro which expands to static_assert when possible?
  • How to write a copyconstructor for a class which has HANDLE as a member in win32 c++ application?
  • C++ saving info such as tree in a file
  • Transforming an expression template tree
  • How to overload an operator with multiple parameters like a + b + c?
  • C++ 11 with Raspberry Pi performances
  • Make a C++ class look like a numpy array using swig
  • Postfix incrementer overloading for nested enumerated types
  • Is there a tidy way of associating metadata with functions in C++
  • QObject::installEventFilter(): Cannot filter events for objects in a different thread
  • LNK2005 error with Zxing C++
  • C++ Doubly Linked List with Pointers: Object of class isn't constructed properly
  • Using a random string generator in c++ constructor
  • What should I use instead of void as one of the alternative types in an variant?
  • C++ return value from multithreads using reference
  • How to connect multiple TCP IP clients to same server port using c++
  • Defaul compiler generates the reference operator (In C++)?
  • Unable to change directory time stamp after using FILE_FLAG_BACKUP_SEMANTICS
  • vector handling displaying output
  • WSAGetLastError returns WSAENOTSOCK - Cause?
  • C++: How to overload pow for user type?
  • C++ using arrays as multidimensional despite initalising it as 1D with pointer
  • How negate std::is_integral for use in tag dispatch?
  • Retrieve serial number from USB memory (Windows environment c++)
  • g++ error: invalid preprocessing directive #INCLUDE
  • C++ What is the std::for_each() function parameter type?
  • C++: Read individual lines from text file, sort words alphabetically
  • Saving 'this' address into a variable
  • c++ command line arguments in ubuntu terminal
  • Convert "Cartesian coordinates" to "polar coordinates with respect to user specified origin"
  • In what order are local scoped objects destructed?
  • How to use SDL_MapRGB with SDL 2.0
  • how compiler and interpreter work in case of array declaration
  • GSL integration behaves strange
  • Cropping an image with OpenCV and C
  • Find the last line in text file and select the first 10 char and print to a new file?
  • Created many CCSprits but when triggering ccTouchBegan gives the last one allways
  • seekp and seekg don't work with fstream
  • Taking input in Sublime Text 3
  • shadow
    Privacy Policy - Terms - Contact Us © ourworld-yourmove.org