关于Qt中QThreadPool的清理

最近学习了下PyQt5编程，遇到一个问题，就是QThreadPool的清理。具体说来就是我有时需要停下一个QThreadPool中所有线程的执行，并做必要的清理。这里的有时主要有两个场景：因为新的输入QThreadPool要清理后从新的输入开始；关闭窗口程序退出。第一个场景中的一个是搜索关键词去网络上抓取图片，抓取是在线程池中执行的，然后返回图片数据通过slot在GUI上显示出来，新的搜索与之前的完全独立。最终成型的代码如下：

import sys
import time
from collections import deque
from PyQt5.QtCore import QObject, QRunnable, QThreadPool
from PyQt5.QtCore import pyqtSignal as Signal
from PyQt5.QtCore import pyqtSlot as Slot
from pyQt5.QtWidgets import QApplication, QMainWindow
import traceback


class WorkerSignals(QObject):
    '''
    Defines the signals available from a running worker thread.

    Supported signals are:

    finished
        No data

    error
        tuple (exctype, value, traceback.format_exc() )

    result
        object data returned from processing, anything

    progress
        int indicating % progress

    '''
    finished = Signal()
    error = Signal(tuple)
    result = Signal(object)
    progress = Signal(int)


class Worker(QRunnable):
    '''
    Worker thread

    Inherits from QRunnable to handler worker thread setup, signals and wrap-up.

    :param callback: The function callback to run on this worker thread. Supplied args and
                     kwargs will be passed through to the runner.
    :type callback: function
    :param args: Arguments to pass to the callback function
    :param kwargs: Keywords to pass to the callback function

    '''

    def __init__(self, fn, *args, **kwargs):
        super().__init__()

        # Store constructor arguments (re-used for processing)
        self.fn = fn
        self.args = args
        self.kwargs = kwargs
        self.signals = WorkerSignals()

        # Add the callback to our kwargs
        self.kwargs['progress_callback'] = self.signals.progress

    @Slot()
    def run