python - 初级Python线程问题

Question

作为使用 Python(使用 pyGTK)进行 GUI 开发的新手，我刚刚开始学习线程。为了测试我的技能，我编写了一个带有开始/停止按钮的简单的小 GTK 界面。目标是当它被点击时，一个线程启动，快速增加文本框中的数字，同时保持 GUI 响应。

我的 GUI 工作得很好，但线程有问题。这可能是一个简单的问题，但我的想法是为了一天而烦恼。下面我首先粘贴了 Python 解释器的引用，然后是代码。你可以去http://drop.io/pxgr5id下载。我正在使用 bzr 进行版本控制，因此如果您想进行修改并重新删除它，请提交更改。我还将代码粘贴在 http://dpaste.com/113388/ 处，因为它可以有行号，而这个 Markdown 的东西让我很头疼。

美国东部时间 1 月 27 日 15:52 更新:可以在这里找到稍微更新的代码:http://drop.io/threagui/asset/thread-gui-rev3-tar-gz

回溯

crashsystems@crashsystems-laptop:~/Desktop/thread-gui$ python threadgui.pybtnStartStop clicked
Traceback (most recent call last):
  File "threadgui.py", line 39, in on_btnStartStop_clicked
    self.thread.stop()
  File "threadgui.py", line 20, in stop
    self.join()
  File "/usr/lib/python2.5/threading.py", line 583, in join
    raise RuntimeError("cannot join thread before it is started")
RuntimeError: cannot join thread before it is started
btnStartStop clicked
threadStop = 1
btnStartStop clicked
threadStop = 0
btnStartStop clicked
Traceback (most recent call last):
  File "threadgui.py", line 36, in on_btnStartStop_clicked
    self.thread.start()
  File "/usr/lib/python2.5/threading.py", line 434, in start
    raise RuntimeError("thread already started")
RuntimeError: thread already started
btnExit clicked
exit() called

代码

#!/usr/bin/bash
import gtk, threading

class ThreadLooper (threading.Thread):
    def __init__ (self, sleep_interval, function, args=[], kwargs={}):
        threading.Thread.__init__(self)
        self.sleep_interval = sleep_interval
        self.function = function
        self.args = args
        self.kwargs = kwargs
        self.finished = threading.Event()

    def stop (self):
        self.finished.set()
        self.join()

    def run (self):
        while not self.finished.isSet():
            self.finished.wait(self.sleep_interval)
            self.function(*self.args, **self.kwargs)

class ThreadGUI:
    # Define signals
    def on_btnStartStop_clicked(self, widget, data=None):
        print "btnStartStop clicked"
        if(self.threadStop == 0):
            self.threadStop = 1
            self.thread.start()
        else:
            self.threadStop = 0
            self.thread.stop()
        print "threadStop = " + str(self.threadStop)

    def on_btnMessageBox_clicked(self, widget, data=None):
        print "btnMessageBox clicked"
        self.lblMessage.set_text("This is a message!")
        self.msgBox.show()

    def on_btnExit_clicked(self, widget, data=None):
        print "btnExit clicked"
        self.exit()

    def on_btnOk_clicked(self, widget, data=None):
        print "btnOk clicked"
        self.msgBox.hide()

    def on_mainWindow_destroy(self, widget, data=None):
        print "mainWindow destroyed!"
        self.exit()

    def exit(self):
        print "exit() called"
        self.threadStop = 1
        gtk.main_quit()

    def threadLoop(self):
        # This will run in a thread
        self.txtThreadView.set_text(str(self.threadCount))
        print "hello world"
        self.threadCount += 1

    def __init__(self):
        # Connect to the xml GUI file
        builder = gtk.Builder()
        builder.add_from_file("threadgui.xml")

        # Connect to GUI widgets
        self.mainWindow = builder.get_object("mainWindow")

        self.txtThreadView = builder.get_object("txtThreadView")
        self.btnStartStop = builder.get_object("btnStartStop")
        self.msgBox = builder.get_object("msgBox")
        self.btnMessageBox = builder.get_object("btnMessageBox")
        self.btnExit = builder.get_object("btnExit")
        self.lblMessage  = builder.get_object("lblMessage")
        self.btnOk = builder.get_object("btnOk")

        # Connect the signals
        builder.connect_signals(self)

        # This global will be used for signaling the thread to stop.
        self.threadStop = 1

        # The thread
        self.thread = ThreadLooper(0.1, self.threadLoop, (1,0,-1))
        self.threadCounter = 0

if __name__ == "__main__":
    # Start GUI instance
    GUI = ThreadGUI()
    GUI.mainWindow.show()
    gtk.main()

Answer 1

如果您想正确地使用 PyGTK 进行线程处理，则有点棘手。基本上，您不应该从主线程以外的任何其他线程中更新 GUI(GUI 库中的常见限制)。通常这是在 PyGTK 中使用排队消息机制(用于 worker 和 GUI 之间的通信)完成的，这些消息使用超时功能定期读取。一旦我在本地 LUG 上就此主题进行了演示，您就可以从 Google Code repository 获取此演示文稿的示例代码。 .查看 forms/frmmain.py 中的 MainWindow 类，特别是方法 _pulse() 以及 on_entry_activate( )(线程在那里启动加上空闲计时器被创建)。

def on_entry_activate(self, entry):
    text = entry.get_text().strip()
    if text:
        store = entry.get_completion().get_model()
        if text not in [row[0] for row in store]:
            store.append((text, ))
        thread = threads.RecommendationsFetcher(text, self.queue)# <- 1
        self.idle_timer = gobject.idle_add(self._pulse)# <- 2
        tv_results = self.widgets.get_widget('tv_results')
        model = tv_results.get_model()
        model.clear()
        thread.setDaemon(True)# <- 3
        progress_update = self.widgets.get_widget('progress_update')
        progress_update.show()
        thread.start()# <- 4

这样，应用程序会在“空闲”(通过 GTK 方式)时更新 GUI，而不会导致卡住。

• 1: 创建线程
• 2:创建空闲计时器
• 3:守护线程，这样应用程序就可以在不等待线程完成的情况下关闭
• 4:启动线程