PyQT 和线程

Question

我正在开发一个应用程序，它使用多个线程从各种网络设备收集数据。我正在使用 PyQT 在 GUI 上显示收集的数据。我在我的应用程序（而不是 QThread）中使用常规的 python 线程（来自线程，线程）。为了更新不同线程上的 GUI，我使用了锁 (thread.allocate_lock())。所以，每当 GUI 更新发生时，我都会用锁调用，更新 GUI。对此有任何顾虑吗？

Answer 1

我很确定在 Qt 中从不同的线程更新 GUI 是危险的，即使您尝试在自己的代码中锁定内容。一方面，Qt 可能在主线程上进行自己的事件处理，它不会获取你的锁来保护它可能修改的对象。 On this page 在 Qt 文档中，明确提到了 QWidget 不是可重入或线程安全的事实。

我建议您将收集到的数据或其处理后的版本发布回主线程。使用排队信号/插槽连接，或自定义QEvent 和QApplication::postEvent 来执行此操作。在 jkerian 提到的上一个问题中，它说如果您希望事件发布正常工作，您必须使用 QThread 而不是 python 的线程。

Answer 2

这是一个迟到的回复，但我想分享我的发现。这是来自 WickedDevice 博客的代码，我发现它有助于理解线程和 PyQt：

#authors: Dirk Swart, Doudewijn Rempt, Jacob Hallen

import sys, time, threading, random, Queue
from PyQt4 import QtGui, QtCore as qt
import serial

SERIALPORT = 'COM6'

class GuiPart(QtGui.QMainWindow):

    def __init__(self, queue, endcommand, *args):
        QtGui.QMainWindow.__init__(self, *args)
        self.setWindowTitle('Arduino Serial Demo')
        self.queue = queue
        # We show the result of the thread in the gui, instead of the console
        self.editor = QtGui.QTextEdit(self)
        self.setCentralWidget(self.editor)
        self.endcommand = endcommand    

    def closeEvent(self, ev):
        self.endcommand()

    def processIncoming(self):
        """
        Handle all the messages currently in the queue (if any).
        """
        while self.queue.qsize():
            try:
                msg = self.queue.get(0)
                # Check contents of message and do what it says
                # As a test, we simply print it
                self.editor.insertPlainText(str(msg))
            except Queue.Empty:
                pass

class ThreadedClient:
    """
    Launch the main part of the GUI and the worker thread. periodicCall and
    endApplication could reside in the GUI part, but putting them here
    means that you have all the thread controls in a single place.
    """
    def __init__(self):
        # Create the queue
        self.queue = Queue.Queue()

        # Set up the GUI part
        self.gui=GuiPart(self.queue, self.endApplication)
        self.gui.show()

        # A timer to periodically call periodicCall :-)
        self.timer = qt.QTimer()
        qt.QObject.connect(self.timer,
                           qt.SIGNAL("timeout()"),
                           self.periodicCall)
        # Start the timer -- this replaces the initial call to periodicCall
        self.timer.start(100)

        # Set up the thread to do asynchronous I/O
        # More can be made if necessary
        self.running = 1
        self.thread1 = threading.Thread(target=self.workerThread1)
        self.thread1.start()

    def periodicCall(self):
        """
        Check every 100 ms if there is something new in the queue.
        """
        self.gui.processIncoming()
        if not self.running:
            root.quit()

    def endApplication(self):
        self.running = 0

    def workerThread1(self):
        """
        This is where we handle the asynchronous I/O. 
        Put your stuff here.
        """
        while self.running:
            #This is where we poll the Serial port. 
            #time.sleep(rand.random() * 0.3)
            #msg = rand.random()
            #self.queue.put(msg)
            ser = serial.Serial(SERIALPORT, 115200)
            msg = ser.readline();
            if (msg):
                self.queue.put(msg)
            else: pass  
            ser.close()



if __name__ == "__main__":
    #rand = random.Random()
    root = QtGui.QApplication(sys.argv)
    client = ThreadedClient()
    sys.exit(app.exec_())

Answer 3

我使用 pyqtSignal 和 Python 的线程。您可以创建线程，并在线程完成后发送信号以更新您的 GUI。