重用 QRunnable

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问题描述

我一直在试验 QRunnable 以便启动和运行一些服务调用.我从 Qt 文档中偶然发现了以下信息:

I have been experimenting with QRunnable in order to get some service calls up and running. I have stumbled across the following piece of information from the Qt documentation:

QThreadPool 支持多次执行相同的 QRunnable从 QRunnable::run() 中调用 tryStart(this).如果自动删除是启用 QRunnable 将在最后一个线程退出时被删除运行功能.使用相同的 QRunnable 多次调用 start()启用 autoDelete 时会产生竞争条件，而不是推荐.

有人可以解释一下这是什么意思吗?我编写了以下代码，它允许我按顺序多次执行 QRunnable 对象:

Can someone explain what this means? I've written the following code and it allows me to execute a QRunnable object multiple times sequentially:

#!/usr/bin/env python

from PyQt4.QtCore import QRunnable, pyqtSlot, pyqtSignal, QObject, QThread, QThreadPool
from PyQt4.QtGui import QApplication, QWidget, QPushButton, QHBoxLayout, QLabel
from sys import exit, argv
from random import getrandbits

class ServiceCallSignals(QObject):
  srv_status = pyqtSignal(bool)
  srv_running = pyqtSignal(bool)

class ServiceCall(QRunnable):

  def __init__(self):
    super(ServiceCall, self).__init__()
    self.signals = ServiceCallSignals()

  def run(self):
    self.signals.srv_running.emit(True)
    call = bool(getrandbits(1))
    print('QRunnable Thread ID: %d' % int(QThread.currentThreadId()))
    if call: QThread.sleep(5)

    self.signals.srv_status.emit(call)
    self.signals.srv_running.emit(False)

class Test(QWidget):

  def __init__(self):
    super(Test, self).__init__()
    self.initUI()

  def initUI(self):

    layout = QHBoxLayout(self)

    self.cb = QPushButton('Send request', self)
    self.cb.clicked.connect(self.srv_send)
    layout.addWidget(self.cb)

    self.lbl = QLabel('Waiting...', self)
    layout.addWidget(self.lbl)

    self.srv = ServiceCall()
    self.srv.setAutoDelete(False)
    self.srv.signals.srv_status.connect(self.srv_receive)
    self.srv.signals.srv_running.connect(self.srv_block)
    self.tp = QThreadPool(self)

    self.setGeometry(300, 300, 250, 150)
    self.setWindowTitle('QRunnable and ROS service calls')
    self.show()

  @pyqtSlot()
  def srv_send(self):
    print('Main Thread ID: %d' % int(QThread.currentThreadId()))
    self.tp.start(self.srv)
    self.cb.setText('Running for reply')

  @pyqtSlot(bool)
  def srv_block(self, state):
    self.cb.setEnabled(not state)

  @pyqtSlot(bool)
  def srv_receive(self, srv_res):
    if srv_res: self.lbl.setText('Success')
    else: self.lbl.setText('Failed')
    self.cb.setText('Send request')

def main():

  app = QApplication(argv)
  t = Test()
  exit(app.exec_())


if __name__ == '__main__':
  main()

文档中的引用是否意味着我做错了?如果我把我的 QThreadPool 和使用 tryStart(self)在我的跑步中，我运行了很多很多线程......

Does the quote from the documentation mean that I'm doing it wrong? If I put my QThreadPool and use tryStart(self) inside my run I get many, many threads running...

QThreadPool

问题描述

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