Python:如何将多进程链接到多进度条

Question

看来我已经非常接近能够将子处理的 Pool() 启动的所有子进程链接到 PyQt 进度条小部件了。这是示例代码。显然没有什么流程可以阻止我的梦想发生。

概念:

externalFunc() 执行所有主要任务。有时，它通过将其 VALUE 存储到用以下方式声明的 poolDict 变量中，将其“进度值”发送到 MainWindow() 实例:

poolDict=manager.dict()

同时，myEvenListener() 方法正在后台运行，等待“发布”VALUE。一旦“收到”VALUE，myEvenListener() 就会将 ProgressBar 更新为收到的 VALUE 并将其重置为零(以避免重复的 ProgressBar 更新)。myEvenListener(self) 在尝试更新 ProgressBar 之前验证 ProgressBar 尚未达到其最大值 100，然后再继续使用:

if pb.value()>=100: continue

不幸的是，即使 externalFunc() 提供了足够多的值 (160)，ProgressBar 也永远不会达到 100。除此之外，没有办法退出 MainWindow() while 循环。

在阅读此代码之前请小心运行它，因为它可能会在您的计算机上生成必须终止的多个 python 进程。

问题:

1. 为什么 ProgressBar 永远不会达到最大值 100
2. 如何确保 myEvenListener() 方法在不需要时不运行。
3. 如何确保所有子进程在以下情况后终止:A。所有进度条都处于 100%b.用户关闭对话框或终止主进程。

<小时/>

import sys, time
from PyQt4 import QtCore, QtGui

import multiprocessing as mp
from multiprocessing import Pool
manager = mp.Manager()

poolDict=manager.dict()

class PbWidget(QtGui.QProgressBar):
    def __init__(self, parent=None, total=20):
        super(PbWidget, self).__init__()
        self.setMinimum(1)
        self.setMaximum(total)        
        self._active = False  

    def update_bar(self, to_add_number):
        while True:
            time.sleep(0.01)
            value = self.value() + to_add_number            
            self.setValue(value)
            QtGui.qApp.processEvents()
            if (not self._active or value >= self.maximum()):                
                break
        self._active = False

    def closeEvent(self, event):
        self._active = False


def externalFunc(each):
    for i in range(16):
        print i
        poolDict[each]=10+i 
        time.sleep(0.5)


class MainWindow(QtGui.QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        # self.myList=[.1, .3, .5, 1.0, 1.5, 2.9, 3.1]
        self.myList=[1]
        self.main_layout = QtGui.QVBoxLayout()
        self.pBars={}
        self.state=True

        for each in self.myList:
            pb=PbWidget(total=101)
            self.main_layout.addWidget(pb)
            self.pBars[each]={'pb':pb, 'value':0, 'total_value':0} 

        ok_button = QtGui.QPushButton("OK")
        ok_button.clicked.connect(self.OK)      
        self.main_layout.addWidget(ok_button)       

        central_widget = QtGui.QWidget()
        central_widget.setLayout(self.main_layout)
        self.setCentralWidget(central_widget)

    def myEvenListener(self):
        """This function runs at the background as an infinite while loop. It constantly reads 
        a value stored in poolDict variable to which externalFunc() writes a new value every second. 
        The value represents a 'Progress' and needs to be passes to Progress Bar widget to which only MainWindow() 
        class has an access. After a Value was read it is used to update a Progress Bar. 
        After a progress bar was updated the Value is reset to zero. 
        The Problem: 'if pb.value()>=100' statement is used to make sure the function doesn't loop if the ProgressBar
        is already reached 100. By some reason the bar never reaches its maximum 100 even while externalFunc() calls
        enough times to reach this number. An ussue # 2: There is no meachanism to exit this while loop without adding
        three more variables... Can it be achieved with what we already have? 
        """
        while self.state:    
            for each in self.pBars:
                pb = self.pBars[each]['pb']
                print "\n Current Bar value =", pb.value()
                if pb.value()>=100:
                    print 'skipping'
                    continue

                value=None
                if each in poolDict.keys(): 
                    # read delivered value
                    delivered_value=poolDict[each]
                    # reset delivered value
                    poolDict[each]=0
                    # update bar with delivered value
                    if ( 101-pb.value() ) < delivered_value:
                        print "\n\t UPDATING WITH "
                        pb.update_bar( 101-pb.value() )
                        print "\n\t AFTER ", pb.value()
                    else:
                        pb.update_bar( delivered_value )
                    # print '\n\t\t\t  Updating bar using this value', delivered_value


    def OK(self):
        pool = Pool(processes=3)
        pool.map_async( externalFunc, self.myList)
        self.myEvenListener()

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    window = MainWindow()
    window.resize(480, 320)
    window.show()
    sys.exit(app.exec_())

Answer 1

这是修改后的代码。看起来运行良好并且相当稳定。

import sys, time
from PyQt4 import QtCore, QtGui

import multiprocessing as mp
from multiprocessing import Pool
manager = mp.Manager()
poolDict=manager.dict()

class PbWidget(QtGui.QProgressBar):
    def __init__(self, parent=None, total=20):
        super(PbWidget, self).__init__()
        self.setMinimum(1)
        self.setMaximum(total)        
        self._active = False  

    def update_bar(self, to_add_number):
        while True:
            time.sleep(0.01)
            value = self.value() + to_add_number            
            self.setValue(value)
            QtGui.qApp.processEvents()
            if (not self._active or value >= self.maximum()):                
                break
        self._active = False

    def closeEvent(self, event):
        self._active = False


def externalFunc(each):
    for i in range(16):
        value =10+i
        poolDict[each]=value    
        time.sleep(each)


class MainWindow(QtGui.QMainWindow):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.myList=[.5, .8, 1.2, 1.8, 2.2, .3, .1]

        self.main_layout = QtGui.QVBoxLayout()
        self.pBars={}
        self.state=True
        self.name=None

        for each in self.myList:
            pb=PbWidget(total=101)
            self.main_layout.addWidget(pb)
            self.pBars[each]={'pb':pb, 'name':each} 

        ok_button = QtGui.QPushButton("Distribute")
        ok_button.clicked.connect(self.OK)      
        self.main_layout.addWidget(ok_button)       

        central_widget = QtGui.QWidget()
        central_widget.setLayout(self.main_layout)
        self.setCentralWidget(central_widget)

    def myEvenListener(self):
        """This function runs at the background as an infinite loop. It is constantly reading
        a value stored in poolDict variable to which externalFunc() writes a new value. 
        The value represents a 'Progress' and needs to be passed to Progress Bar widget to which MainWindow() 
        class has an access. After a Value was read and used to update a Progress Bar it is reset to zero.       
        """ 
        entities = self.pBars.keys()
        while self.state:    
            for each in entities:
                if each not in self.pBars.keys():   continue    

                pb = self.pBars[each]['pb']
                if pb.value()>=100:
                    self.pBars.pop(each, None)

                value=None
                if each in poolDict.keys():
                    # read delivered value
                    delivered_value=poolDict[each]
                    # reset delivered value
                    poolDict[each]=0
                    # update bar with delivered value
                    if ( 101-pb.value() ) < delivered_value:
                        pb.update_bar( 101-pb.value() )                     
                    elif delivered_value>0:
                        pb.update_bar( delivered_value )

                if len(self.pBars.keys())==0:
                    self.state=False

    def OK(self):       
        pool = Pool(processes=3)
        pool.map_async( externalFunc, self.myList)
        self.myEvenListener()

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    window = MainWindow()
    window.resize(480, 320)
    window.show()
    sys.exit(app.exec_())