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Packaging a threaded program with Qt GUI


Packaging a threaded program with Qt GUI

By : user2949643
Date : November 17 2020, 01:00 AM
like below fixes the issue You do not subclass QThread to run something in a different thread. QThread is used via signals/slots.
http://doc.qt.io/qt-5/qthread.html#started
code :
void my_function(int a, double b) {
     .... do something in another thread ....
}
    ....
    auto some_function = std::function<void(int, double)>(&my_function);
    QFuture<void> ret = QtConcurrent::run(some_function, 10, 20.0);
    ....
QFuture<void> ret = QtConcurrent::run(&my_function, 10, 20.0);
class Foo {
public:
     void foo(int a) {}
};

...
Foo *foo_instance = new Foo;
QFuture<void> ret = Qtconcurrent::run(foo_instance, &Foo::foo, 10);
...


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C: How can a threaded program run faster than a non-threaded on the same single core?

C: How can a threaded program run faster than a non-threaded on the same single core?


By : Luis
Date : March 29 2020, 07:55 AM
around this issue Because you are simulating the "work" by sleeping. So the scheduler need only put one thread to sleep for 5 seconds; afterwards it is free to "service" another thread.
In short, you aren't using the CPU so in theory you could service a lot of clients this way. Now if you were to do something CPU-bound for 5 seconds, you would see the difference.
Multi threaded program takes longer to execute than the Single Threaded Program

Multi threaded program takes longer to execute than the Single Threaded Program


By : user32308
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further First of all, you are using processor-clock ticks to measure the performance, and by that measure any multi-threaded algorithm will be slower than an equivalent single-threaded algorithm. The reason is because this measure effectively counts the number of instructions that gets executed and threading always adds a little overhead to an algorithm.
To get a proper measurement of performance, you need to measure the wall-clock time. This way, the measurement can accurately reflect the work that gets done in parallel by different cores/processors.
Single Threaded Program vs Multithreaded Program (measuing time elapsed)

Single Threaded Program vs Multithreaded Program (measuing time elapsed)


By : Thomas Kgaevski
Date : March 29 2020, 07:55 AM
may help you . Your multi-threaded program likely makes all the requests at the same time which puts more strain on the server which will cause it to respond slower to all request.
As an aside, the way you are doing the update isn't threadsafe, so your count will likely be off in the multithreaded scenario given enough trials.
Multi-Threaded program runs slower than single threaded

Multi-Threaded program runs slower than single threaded


By : 지향은
Date : March 29 2020, 07:55 AM
I wish did fix the issue.
I understand that the result will not be correct but it is crawling compared to single threaded one
GDB hangs when multi-threaded python extension is used to debug multi threaded program

GDB hangs when multi-threaded python extension is used to debug multi threaded program


By : kishore dasari
Date : March 29 2020, 07:55 AM
I wish this help you From this blog post:
code :
import gdb
import threading
import pysigset, signal # Import these packages!

def plot_thread():
    import time
    while True:
        print('Placeholder for a window event loop.')
        time.sleep(1)
        pass
    pass

class PlotterCommand(gdb.Command):
    def __init__(self):
        super(PlotterCommand, self).__init__("plot",
                                            gdb.COMMAND_DATA,
                                            gdb.COMPLETE_SYMBOL)
        self.dont_repeat()
        pass

    def invoke(self, arg, from_tty):
        with pysigset.suspended_signals(signal.SIGCHLD): # Disable signals here!
            plot_thread_instance=threading.Thread(target=plot_thread)
            plot_thread_instance.daemon=True
            plot_thread_instance.start()
            pass
        pass

    pass

PlotterCommand()
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