Yet another "keeping the GUI responsive"

[dubbaluga]

Hi all,

I'm heaving problems with offloading some CPU-intensive calculations to a separate thread. My GUI's response is too slow, sometimes it takes several seconds to repaint/refresh. I have a dual-core CPU with recent amd64-Linux running.

Maybe there is some misunderstanding: so far I thought it's only about starting the background thread and let it go. I have been reading Keeping the GUI responsive but it has not really help me yet. As you can see in the code (below), my thread does not do anything useful except from eating loads of CPU-cycles.

Here is what I've tried so far:

• Invoking QtCore.QCoreApplication.processEvents() (line 20, 23-26)
• Setting thread priority (line 58)
• Instantiating a worker-object on the stack of the thread and invoking the worker's method using QtCore.QTimer.singleShot() to make sure processed data only lives on the thread's stack

The only thing that helped me a little bit was setting the thread priority. Is there anything I can do to let my program have a better response time? I'm especially interested in solutions that work with third-party code, meaning invoking CPU-intensive methods from external libraries which I cannot extend with Qt-related functionality.

Thank you for your support in advance,
Rainer

import sys
from PySide import QtGui, QtCore, QtUiTools
 
# Import the compiled UI module
from customwidget import Ui_customWidget
 
 
class CCalculation(QtCore.QThread):
 
    sProgress = QtCore.Signal(int)
    sFinished = QtCore.Signal()
 
    def __init__(self, pData):
        super(CCalculation, self).__init__()
        self.mData = pData
 
    def run(self):
        lCnt = 0
        lTotal = len(self.mData)
#        lLast = datetime.datetime.now()
        for lNum in self.mData:
            self.mData[lCnt] = lNum ** 2
#            lNow = datetime.datetime.now()
#            if (lNow - lLast) > datetime.timedelta(0, 0, 100000):
#                lLast = lNow
#                QtCore.QCoreApplication.processEvents()
            if 100 * lCnt / lTotal % 10 == 0:
                self.sProgress.emit(100 * lCnt / lTotal)
            lCnt = 0
        self.sFinished.emit()
 
class CMain:
 
    sNumElements = 200000
    sAccessElement = 22
 
    def __init__(self):
        # GUI code
        self.mApp = QtGui.QApplication(sys.argv)
        self.mWindow = QtGui.QMainWindow()
        self.mWidget = QtGui.QWidget()
        self.mFactory = Ui_customWidget()
        self.mFactory.setupUi(self.mWidget)
        self.mWindow.setCentralWidget(self.mWidget)
 
        # Threading
        self.mData = range(CMain.sNumElements)
        self.mThread = CCalculation(self.mData)
        self.mThreadRunning = QtCore.QMutex()
 
        # wire signals and slots
        self.mThread.sProgress.connect(self.mFactory.progressBar.setValue)
        self.mThread.sFinished.connect(self.threadFinished)
        self.mFactory.processButton.clicked.connect(self.startThread)
 
    def startThread(self):
        if self.mThreadRunning.tryLock() == True:
            #self.mThread.start(QtCore.QThread.IdlePriority)
            self.mThread.start()
 
    def threadFinished(self):
        self.mFactory.textEdit.setText(str(self.mData[CMain.sAccessElement]))
        self.mThreadRunning.unlock()
 
    def run(self):
        self.mWindow.show()
        lReturn = self.mApp.exec_()
        self.mThread.quit()
        self.mThread.wait()
        sys.exit(lReturn)
 
 
if __name__ == "__main__":
    lMain = CMain()
    lMain.run()

import sys
from PySide import QtGui, QtCore, QtUiTools

# Import the compiled UI module
from customwidget import Ui_customWidget


class CCalculation(QtCore.QThread):

    sProgress = QtCore.Signal(int)
    sFinished = QtCore.Signal()

    def __init__(self, pData):
        super(CCalculation, self).__init__()
        self.mData = pData

    def run(self):
        lCnt = 0
        lTotal = len(self.mData)
#        lLast = datetime.datetime.now()
        for lNum in self.mData:
            self.mData[lCnt] = lNum ** 2
#            lNow = datetime.datetime.now()
#            if (lNow - lLast) > datetime.timedelta(0, 0, 100000):
#                lLast = lNow
#                QtCore.QCoreApplication.processEvents()
            if 100 * lCnt / lTotal % 10 == 0:
                self.sProgress.emit(100 * lCnt / lTotal)
            lCnt = 0
        self.sFinished.emit()

class CMain:

    sNumElements = 200000
    sAccessElement = 22

    def __init__(self):
        # GUI code
        self.mApp = QtGui.QApplication(sys.argv)
        self.mWindow = QtGui.QMainWindow()
        self.mWidget = QtGui.QWidget()
        self.mFactory = Ui_customWidget()
        self.mFactory.setupUi(self.mWidget)
        self.mWindow.setCentralWidget(self.mWidget)

        # Threading
        self.mData = range(CMain.sNumElements)
        self.mThread = CCalculation(self.mData)
        self.mThreadRunning = QtCore.QMutex()

        # wire signals and slots
        self.mThread.sProgress.connect(self.mFactory.progressBar.setValue)
        self.mThread.sFinished.connect(self.threadFinished)
        self.mFactory.processButton.clicked.connect(self.startThread)

    def startThread(self):
        if self.mThreadRunning.tryLock() == True:
            #self.mThread.start(QtCore.QThread.IdlePriority)
            self.mThread.start()

    def threadFinished(self):
        self.mFactory.textEdit.setText(str(self.mData[CMain.sAccessElement]))
        self.mThreadRunning.unlock()

    def run(self):
        self.mWindow.show()
        lReturn = self.mApp.exec_()
        self.mThread.quit()
        self.mThread.wait()
        sys.exit(lReturn)


if __name__ == "__main__":
    lMain = CMain()
    lMain.run()

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[wysota]

Does not emitting the progress signal bring back responsiveness of the UI?