pyqt从线程发出信号

Question

我试图从多个线程更新pyqt QProgressBar，据我所知，最好的方法是将信号发送回主GUI线程（我尝试将QProgressBar对象传递给工作线程，尽管它看起来确实有效，但在解释器中收到了大量警告）。在下面的代码中，我设置了一个progressSignal信号，并将其连接到一个线程上，该线程（目前）只打印所发出的任何内容。然后我从每个线程发出总百分比。我知道这是在线程外工作的，它只在第47行抛出一个随机的emit，它确实通过了。然而，第36行的发射不会触发任何东西，所以它似乎永远无法通过。。。在

import Queue, threading
from PyQt4 import QtCore
import shutil
import profile

fileQueue = Queue.Queue()

class Communicate(QtCore.QObject):

    progressSignal = QtCore.pyqtSignal(int)

class ThreadedCopy:
    totalFiles = 0
    copyCount = 0
    lock = threading.Lock()

    def __init__(self, inputList, progressBar="Undefined"):
        self.totalFiles = len(inputList)

        self.c = Communicate()
        self.c.progressSignal.connect(self.updateProgressBar)

        print str(self.totalFiles) + " files to copy."
        self.threadWorkerCopy(inputList)


    def CopyWorker(self):
        while True:
            self.c.progressSignal.emit(2000)
            fileName = fileQueue.get()
            shutil.copy(fileName[0], fileName[1])
            fileQueue.task_done()
            with self.lock:
                self.copyCount += 1
                percent = (self.copyCount * 100) / self.totalFiles
                self.c.progressSignal.emit(percent)

    def threadWorkerCopy(self, fileNameList):

        for i in range(16):
            t = threading.Thread(target=self.CopyWorker)
            t.daemon = True
            t.start()
        for fileName in fileNameList:
            fileQueue.put(fileName)
        fileQueue.join()
        self.c.progressSignal.emit(1000)

    def updateProgressBar(self, percent):
        print percent

更新：

这是一个带有图形用户界面的示例。这一个运行，但非常不稳定，它经常崩溃，用户界面做一些奇怪的事情（进度条没有完成，等等）

在主.py以下内容：

^{pr2}$

多线程副本_5.py：

import Queue, threading
from PyQt4 import QtCore
import shutil
import profile

fileQueue = Queue.Queue()

class Communicate(QtCore.QObject):

    progressSignal = QtCore.pyqtSignal(int)

class ThreadedCopy:
    totalFiles = 0
    copyCount = 0
    lock = threading.Lock()

    def __init__(self, inputList, progressBar="Undefined"):
        self.progressBar = progressBar
        self.totalFiles = len(inputList)

        self.c = Communicate()
        self.c.progressSignal.connect(self.updateProgressBar, QtCore.Qt.DirectConnection)

        print str(self.totalFiles) + " files to copy."
        self.threadWorkerCopy(inputList)


    def CopyWorker(self):
        while True:
            fileName = fileQueue.get()
            shutil.copy(fileName[0], fileName[1])
            fileQueue.task_done()
            with self.lock:
                self.copyCount += 1
                percent = (self.copyCount * 100) / self.totalFiles
                self.c.progressSignal.emit(percent)

    def threadWorkerCopy(self, fileNameList):
        for i in range(16):
            t = threading.Thread(target=self.CopyWorker)
            t.daemon = True
            t.start()
        for fileName in fileNameList:
            fileQueue.put(fileName)
        fileQueue.join()

    def updateProgressBar(self, percent):
        self.progressBar.setValue(percent)

#profile.run('ThreadedCopy()')

Answer 1

主要问题是发送信号和接收信号之间的时间延迟，我们可以使用^{}来缩短时间：

You can call this function occasionally when your program is busy performing a long operation (e.g. copying a file).

def CopyWorker(self):
    while True:
        fileName = fileQueue.get()
        shutil.copy(fileName[0], fileName[1])
        fileQueue.task_done()
        with self.lock:
            self.copyCount += 1
            print(self.copyCount)
            percent = (self.copyCount * 100) / self.totalFiles
            self.c.progressSignal.emit(percent)
            QtCore.QCoreApplication.processEvents()

Answer 2

你的例子有两个主要问题。在

首先，发出信号的对象是在main/gui线程中创建的，因此它发出的任何信号都不会是跨线程的，因此不是线程安全的。显而易见的解决方案是在工作线程的目标函数内部创建信令对象，这意味着每个线程都必须有一个单独的实例。在

其次，目标函数中的while循环永远不会终止，这意味着在当前复制操作完成后，每个ThreadedCopy对象都将保持活动状态。由于所有这些对象共享同一个队列，如果试图重复复制操作，行为将变得不可预测。显而易见的解决方案是，一旦队列为空，就跳出while循环。在

下面是对MultithreadedCopy_5.py的重写，应该可以解决这些问题。但是，正如评论中所述，我仍然强烈建议在这个场景中使用QThread而不是python线程，因为它可能提供一个更健壮、更易于维护的解决方案。在

import Queue, threading
from PyQt4 import QtCore
import shutil
import profile

fileQueue = Queue.Queue()

class Communicate(QtCore.QObject):
    progressSignal = QtCore.pyqtSignal(int)

class ThreadedCopy:
    totalFiles = 0
    copyCount = 0
    lock = threading.Lock()

    def __init__(self, inputList, progressBar="Undefined"):
        self.progressBar = progressBar
        self.totalFiles = len(inputList)
        print str(self.totalFiles) + " files to copy."
        self.threadWorkerCopy(inputList)

    def CopyWorker(self):
        c = Communicate()
        c.progressSignal.connect(self.updateProgressBar)
        while True:
            try:
                fileName = fileQueue.get(False)
            except Queue.Empty:
                break
            else:
                shutil.copy(fileName[0], fileName[1])
                with self.lock:
                    self.copyCount += 1
                    percent = (self.copyCount * 100) / self.totalFiles
                    c.progressSignal.emit(percent)
                fileQueue.task_done()

    def threadWorkerCopy(self, fileNameList):
        if fileQueue.empty():
            for i in range(16):
                t = threading.Thread(target=self.CopyWorker)
                t.daemon = True
                t.start()
            for fileName in fileNameList:
                fileQueue.put(fileName)
            fileQueue.join()

    def updateProgressBar(self, percent):
        self.progressBar.setValue(percent)