您好, 欢迎来到 !    登录 | 注册 | | 设为首页 | 收藏本站

在Python中,我怎么知道进程何时完成?

在Python中,我怎么知道进程何时完成?

这个答案真的很简单!(花了我 几天的时间解决。)

与PyGTK的idle_add()结合使用,可以创建一个AutoJoiningThread。总代码是微不足道的:

class AutoJoiningThread(threading.Thread):
    def run(self):
        threading.Thread.run(self)
        gobject.idle_add(self.join)

如果您想做的不只是加入(例如收集结果),还可以扩展上面的类以在完成时发出信号,如以下示例所示:

import threading
import time
import sys
import gobject
gobject.threads_init()

class Child:
    def __init__(self):
        self.result = None

    def play(self, count):
        print "Child starting to play."
        for i in range(count):
            print "Child playing."
            time.sleep(1)
        print "Child finished playing."
        self.result = 42

    def get_result(self, obj):
        print "The result was "+str(self.result)

class AutoJoiningThread(threading.Thread, gobject.GObject):
    __gsignals__ = {
        'finished': (gobject.SIGNAL_RUN_LAST,
                     gobject.TYPE_NONE,
                     ())
        }

    def __init__(self, *args, **kwargs):
        threading.Thread.__init__(self, *args, **kwargs)
        gobject.GObject.__init__(self)

    def run(self):
        threading.Thread.run(self)
        gobject.idle_add(self.join)
        gobject.idle_add(self.emit, 'finished')

    def join(self):
        threading.Thread.join(self)
        print "Called Thread.join()"

if __name__ == '__main__':
    print "Creating child"
    child = Child()
    print "Creating thread"
    thread = AutoJoiningThread(target=child.play,
                               args=(3,))
    thread.connect('finished', child.get_result)
    print "Starting thread"
    thread.start()
    print "Running mainloop (Ctrl+C to exit)"
    mainloop = gobject.MainLoop()

    try:
        mainloop.run()
    except KeyboardInterrupt:
        print "Received KeyboardInterrupt.  Quiting."
        sys.exit()

    print "God kNows how we got here.  Quiting."
    sys.exit()

上面示例的输出将取决于线程执行的顺序,但是它将类似于:

创造孩子
创建线程
启动线程
孩子开始玩。
 小孩玩。
运行主循环(Ctrl + C退出)
小孩玩。
小孩玩。
孩子玩完了。
叫做Thread.join()
结果是42
^ C收到KeyboardInterrupt。退出

以相同的方式创建AutoJoiningProcess是不可能的(因为我们不能在两个不同的进程之间调用idle_add()),但是我们可以使用AutoJoiningThread来获得我们想要的:

class AutoJoiningProcess(multiprocessing.Process):
    def start(self):
        thread = AutoJoiningThread(target=self.start_process)
        thread.start() # automatically joins

    def start_process(self):
        multiprocessing.Process.start(self)
        self.join()

为了演示AutoJoiningProcess,这里是另一个示例:

import threading
import multiprocessing
import time
import sys
import gobject
gobject.threads_init()

class Child:
    def __init__(self):
        self.result = multiprocessing.Manager().list()

    def play(self, count):
        print "Child starting to play."
        for i in range(count):
            print "Child playing."
            time.sleep(1)
    print "Child finished playing."
        self.result.append(42)

    def get_result(self, obj):
        print "The result was "+str(self.result)

class AutoJoiningThread(threading.Thread, gobject.GObject):
    __gsignals__ = {
        'finished': (gobject.SIGNAL_RUN_LAST,
                     gobject.TYPE_NONE,
                     ())
    }

    def __init__(self, *args, **kwargs):
        threading.Thread.__init__(self, *args, **kwargs)
        gobject.GObject.__init__(self)

    def run(self):
        threading.Thread.run(self)
        gobject.idle_add(self.join)
        gobject.idle_add(self.emit, 'finished')

    def join(self):
        threading.Thread.join(self)
        print "Called Thread.join()"

class AutoJoiningProcess(multiprocessing.Process, gobject.GObject):
    __gsignals__ = {
        'finished': (gobject.SIGNAL_RUN_LAST,
                     gobject.TYPE_NONE,
                     ())
        }

    def __init__(self, *args, **kwargs):
        multiprocessing.Process.__init__(self, *args, **kwargs)
        gobject.GObject.__init__(self)

    def start(self):
        thread = AutoJoiningThread(target=self.start_process)
        thread.start()

    def start_process(self):
        multiprocessing.Process.start(self)
        self.join()
        gobject.idle_add(self.emit, 'finished')

    def join(self):
        multiprocessing.Process.join(self)
        print "Called Process.join()"

if __name__ == '__main__':
    print "Creating child"
    child = Child()
    print "Creating thread"
    process = AutoJoiningProcess(target=child.play,
                               args=(3,))
    process.connect('finished',child.get_result)
    print "Starting thread"
    process.start()
    print "Running mainloop (Ctrl+C to exit)"
    mainloop = gobject.MainLoop()

    try:
        mainloop.run()
    except KeyboardInterrupt:
        print "Received KeyboardInterrupt.  Quiting."
        sys.exit()

    print "God kNows how we got here.  Quiting."
    sys.exit()

产生的输出将与上面的示例非常相似,除了这次我们同时具有流程联接和伴随的线程联接:

创造孩子
创建线程
启动线程
运行主循环(Ctrl + C退出)
 孩子开始玩。
小孩玩。
小孩玩。
小孩玩。
孩子玩完了。
称为Process.join()
结果是[42]
叫做Thread.join()
^ C收到KeyboardInterrupt。退出

不幸:

因此,要使用这种方法,最好只在mainloop / GUI中创建线程/进程。

python 2022/1/1 18:39:37 有512人围观

撰写回答


你尚未登录,登录后可以

和开发者交流问题的细节

关注并接收问题和回答的更新提醒

参与内容的编辑和改进,让解决方法与时俱进

请先登录

推荐问题


联系我
置顶