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Dear all,

I am new to PyQt but I developed GUI apps in my past. I want to make a GUI in which a part is refreshed by a Thread. I tried to understand in the internet how it works and I made the following code (see below).

What I do :

I create a "worker" class that inherits from QObject. From this worker class I print the threadID ( QThread.currentThreadId() )

this worker is instanciated in the window object. It is run through a QThread after a moveToThread operation from the window.

The worker sends signals to the window while it loops. The signal itself prints its threadID too

I added a timer to the window to display again the threadID in which the window runs.

I obtain the same threadID in all the cases and I doubt my worker or my threadID display works well. Can you help ?

Here comes the code, and then the results.

Best Regards,

#!/opt/miniconda3/bin/python3.7
from PyQt5.QtCore import QObject, QThread, pyqtSignal,QTimer
from PyQt5.QtWidgets import QApplication,QMainWindow
from time import sleep
import sys
class Worker(QObject):
    finished = pyqtSignal()
    progress = pyqtSignal()
    def run(self):
        """Long-running task."""
        while True:
            sleep(0.5)
            print("in Worker Thread : ", QThread.currentThreadId())
            self.progress.emit()
        self.finished.emit()
class Window(QMainWindow):
    def __init__(self,*args,**kwargs):
        super().__init__(*args,**kwargs)
        self.runLongTask()
    def workerProgress(self):
        print("Report Thread : ",QThread.currentThreadId())
        print("\n")
    def mainAppProgress(self):
        print("Timer Thread : ",QThread.currentThreadId())
    def runLongTask(self):
        # run the worker using a thread
        self.thread = QThread()
        self.worker = Worker()
        self.worker.moveToThread(self.thread)
        self.thread.started.connect(self.worker.run)
        self.worker.progress.connect(self.workerProgress)
        self.thread.start()
        # run a timer to display the window thread too
        self.timer = QTimer()
        self.timer.setInterval(500)
        self.timer.timeout.connect(self.mainAppProgress)
        self.timer.start()
app = QApplication(sys.argv)
win = Window()
win.show()
sys.exit(app.exec())
Results
Timer Thread :  <sip.voidptr object at 0x10079f0f0>
in Worker Thread :  <sip.voidptr object at 0x10079f0f0>
Report Thread :  <sip.voidptr object at 0x10079f0f0>
Timer Thread :  <sip.voidptr object at 0x10079f0f0>
in Worker Thread :  <sip.voidptr object at 0x10079f0f0>
Report Thread :  <sip.voidptr object at 0x10079f0f0>
Timer Thread :  <sip.voidptr object at 0x10079f0f0>
in Worker Thread :  <sip.voidptr object at 0x10079f0f0>
Report Thread :  <sip.voidptr object at 0x10079f0f0>
Timer Thread :  <sip.voidptr object at 0x10079f0f0>
in Worker Thread :  <sip.voidptr object at 0x10079f0f0>
Report Thread :  <sip.voidptr object at 0x10079f0f0>
Timer Thread :  <sip.voidptr object at 0x10079f0f0>
in Worker Thread :  <sip.voidptr object at 0x10079f0f0>
Report Thread :  <sip.voidptr object at 0x10079f0f0>
Timer Thread :  <sip.voidptr object at 0x10079f0f0>
in Worker Thread :  <sip.voidptr object at 0x10079f0f0>
Report Thread :  <sip.voidptr object at 0x10079f120>
			
@Mika-L What you are printing is the python object, if you want to get the id of the thread then use int():
int(QThread.currentThreadId())
Output:
in Worker Thread :  140448685921856
Report Thread :  140448915945280
Timer Thread :  140448915945280
in Worker Thread :  140448685921856
Report Thread :  140448915945280
Timer Thread :  140448915945280
in Worker Thread :  140448685921856
Report Thread :  140448915945280
If you want to check if the function is executed in the main thread then compare the QThread.currentThread() with QCoreApplication.instance().thread():
print("is executed main thread?",  QThread.currentThread() is QCoreApplication.instance().thread())
Another alternative is to use the threading.current_thread() function:
Timer Thread :  <_MainThread(MainThread, started 140013290776384)>
in Worker Thread :  <_DummyThread(Dummy-1, started daemon 140013060752960)>
Report Thread :  <_MainThread(MainThread, started 140013290776384)>
Timer Thread :  <_MainThread(MainThread, started 140013290776384)>
in Worker Thread :  <_DummyThread(Dummy-1, started daemon 140013060752960)>
Report Thread :  <_MainThread(MainThread, started 140013290776384)>
			
@eyllanesc : very very nice answer ! thanks a lot ! That really helps !
I have a last question : is there somewhere a tool to display the CPU consumption for a given thread, cross-platform ? Or a pythonic tool ?
Thanks again,