subprocess can not kill when app exit()

[不坏阿峰]

Dear all

code in below,  when close the app window.  the two ping process can not kill auto and keep in the windows 7 task list.

During running, ping process under Python.exe as two thread. When app exit,  this two process move the system process and keep running there.

could someone help to correct it.?
Many thanks.

############################
# -*- coding: utf-8 -*-
 
import sys
import time
import subprocess
from threading import Thread
import re
from PyQt4.QtGui import QMainWindow, QApplication, QStandardItemModel, QStandardItem, QWidget, QVBoxLayout, QTableView
from PyQt4.QtCore import pyqtSignature, Qt, QTimer, SIGNAL, QString, QMetaObject
from Queue import Queue

try:
    _fromUtf8 = QString.fromUtf8
except AttributeError:
    _fromUtf8 = lambda s: s
 
class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(500, 435)
        self.centralWidget = QWidget(MainWindow)
        self.centralWidget.setObjectName(_fromUtf8("centralWidget"))
        self.verticalLayout = QVBoxLayout(self.centralWidget)
        self.verticalLayout.setObjectName(_fromUtf8("verticalLayout"))
        self.tableView = QTableView(self.centralWidget)
        self.tableView.setObjectName(_fromUtf8("tableView"))
        self.verticalLayout.addWidget(self.tableView)
        MainWindow.setCentralWidget(self.centralWidget)
 
        self.retranslateUi(MainWindow)
        QMetaObject.connectSlotsByName(MainWindow)
 
    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(QApplication.translate("MainWindow", "Ping Tester", None, QApplication.UnicodeUTF8))
 
if sys.platform.startswith('linux'):
    getdata = re.compile(r"icmp_req=(\d+) ttl=(\d+) time=([\d\.]+)\sms")
    pingstr = ["ping", "-n", "-i 0.2"]
    filtered = "Packet filtered"
    delaytime = 200
else:
    getdata = re.compile(r"=([\d\.]+)ms TTL=(\d+)")
    pingstr = ["ping.exe", "-t"]
    timeout = "Request timed out."
    delaytime = 500
 
try:
    with open("ips.conf", "r") as f:
        t_node = f.read().decode('utf-8')
        if not t_node:
            raise IOError
except IOError:
    with open("ips.conf", "w") as f:
        t_node = u"""
        8.8.8.8-Google
        184.22.112.34-USAHE
        """
        f.write(t_node.encode('utf-8'))
 
node = []
for line in t_node.split('\n'):
    try:
        ip, desc = line.strip().split("-")
        node.append((ip, desc))
    except ValueError:
        pass
nodecount = len(node)
 
class MainWindow(QMainWindow, Ui_MainWindow):
    """
    Class documentation goes here.
    """
    def __init__(self, parent = None):
        """
        Constructor
        """
        QMainWindow.__init__(self, parent)
        self.setupUi(self)
        self.model = QStandardItemModel()
        self.model.setColumnCount(6)
        self.model.setRowCount(nodecount)
        self.model.setHorizontalHeaderLabels(["IP", "Description", "Loss%", "CurPing", "AvgPing", "TTL"])
        for i, (ip, desc) in enumerate(node):
            self.setitem(i, 0, ip)
            self.setitem(i, 1, desc)
            self.setitem(i, 2, "")
            self.setitem(i, 3, "")
            self.setitem(i, 4, "")
            self.setitem(i, 5, "")
        self.tableView.setModel(self.model)
        for i in range(len(node)):
            self.tableView.setRowHeight(i, 18)
        self.resizetable()
        self.timer = QTimer(self)
        self.connect(self.timer,
                     SIGNAL("timeout()"),
                     self.checkitems)
        self.timer.start(delaytime)
 
    def checkitems(self):
        while not q.empty():
            item = q.get()
            self.chgtxt(*item)
            q.task_done()
        self.resizetable()
 
    def resizetable(self):
        self.tableView.resizeColumnsToContents()
 
    def chgtxt(self, x, y, value):
        self.model.item(x, y).setText(value)
 
    def setitem(self, x, y, value):
        self.model.setItem(x, y, QStandardItem(value))
 
app = QApplication(sys.argv)
ui = MainWindow()
ui.show()
q = Queue()
 
def pinger(i, ip, desc):
    s = ""
    avgping = 0
    count = 0
    timeoutcount = 0
    ret = subprocess.Popen(pingstr + [ip],
                            stdout=subprocess.PIPE)
    while True:
        try:
            s += ret.stdout.read(1)
 
            tryfind = getdata.findall(s)
            if sys.platform.startswith('linux'):
                if len(tryfind) > 0:
                    req, ttl, crtping = tryfind[-1]
                    avgping += float(crtping)
                    count += 1
                    q.put((i, 3, crtping + "ms"))
                    q.put((i, 4, "%.2f" % (avgping * 1.0 / count) + "ms"))
                    q.put((i, 5, ttl))
                    q.put((i, 2, "%.2f" % ((int(req) - count) * 100.0 / int(req))))
                    s = ""
                elif filtered in s:
                    q.put((i, 2, "Failed"))
                    q.put((i, 3, "Failed"))
                    q.put((i, 4, "Failed"))
                    q.put((i, 5, "Failed"))
                    ret.kill()
                    s = ""
            else:
                if len(tryfind) > 0:
                    crtping, ttl = tryfind[-1]
                    avgping += float(crtping)
                    count += 1
                    q.put((i, 3, crtping + "ms"))
                    q.put((i, 4, "%.2f" % (avgping * 1.0 / count) + "ms"))
                    q.put((i, 5, ttl))
                    q.put((i, 2, "%.2f" % (timeoutcount * 100.0 / (count + timeoutcount))))
                elif timeout in s:
                    timeoutcount += 1
                    q.put((i, 2, "-"))
                    q.put((i, 3, "-"))
                    if count:
                        q.put((i, 5, "%.2f" % (timeoutcount * 100.0 / (count + timeoutcount))))
                    else:
                        q.put((i, 5, "-"))
                    s = ""
        except IOError:
            print s
            break
 
def startworkers():
    for i, (ip, desc) in enumerate(node):
        worker = Thread(target=pinger, args=(i, ip, desc))
        worker.setDaemon(True)
        worker.start()
        time.sleep(delaytime / 10000.0)
 
startthread = Thread(target=startworkers)
startthread.setDaemon(True)
startthread.start()
 
sys.exit(app.exec_())

#############################