在QWizardPage.initializePage中调用后，QThread没有运行

Question

我打算在我的应用程序的初始化向导（由PyQT开发）中使用QThread来运行数据库初始化，但我发现在我在initializePage中调用thread.start（）之后线程没有运行：

class DBInitializeWorker(QtCore.QObject):
    finished = QtCore.pyqtSignal()
    failed = QtCore.pyqtSignal('QString')
    progress = QtCore.pyqtSignal(int, int)

    def pg_callbk(self, x, y):
        self.progress.emit(x, y)

    def do_initialize(self):
        from restbooks.service import db_initialize
        print 'dbinit>>>>>>>>>>>>>'
        try:
            db_initialize(pgCallbk=self.pg_callbk)
        except Exception, e:
            self.failed.emit('%s' % e)
        else:
            self.finished.emit()

class InitializeDatabasePage(QtGui.QWizardPage):
    """
    InitializeDatabasePage:
    """

    def __init__(self, parent=None):
        super(InitializeDatabasePage, self).__init__(parent)
        self.setTitle(self.tr("Initilize database..."))
        self.setSubTitle(self.tr("kick star to initialize your system."))

        self.verticalLayout = QtGui.QVBoxLayout(self)
        self.verticalLayout.setObjectName(_fromUtf8("verticalLayout"))
        self.groupBox = QtGui.QGroupBox(self)
        self.groupBox.setTitle(_fromUtf8(""))
        self.groupBox.setObjectName(_fromUtf8("groupBox"))
        self.verticalLayout_2 = QtGui.QVBoxLayout(self.groupBox)
        self.verticalLayout_2.setObjectName(_fromUtf8("verticalLayout_2"))
        self.progressBar_initialize = QtGui.QProgressBar(self.groupBox)
        self.progressBar_initialize.setProperty("value", 24)
        self.progressBar_initialize.setObjectName(_fromUtf8("progressBar_initialize"))
        self.verticalLayout_2.addWidget(self.progressBar_initialize)
        self.label_initialize_msg = QtGui.QLabel(self.groupBox)
        self.label_initialize_msg.setAlignment(QtCore.Qt.AlignCenter)
        self.label_initialize_msg.setObjectName(_fromUtf8("label_initialize_msg"))
        self.verticalLayout_2.addWidget(self.label_initialize_msg)
        self.verticalLayout.addWidget(self.groupBox)
        spacerItem = QtGui.QSpacerItem(20, 40, QtGui.QSizePolicy.Minimum, QtGui.QSizePolicy.Expanding)
        self.verticalLayout.addItem(spacerItem)
        self._db_initialized = False
        self.qthread = QtCore.QThread(self)

    def do_db_initialize(self):

        def pg_callbk(x, y):
            self.progressBar_initialize.setValue(x*100/y)

        def init_finished():
            self.label_initialize_msg.setText(self.tr("Database initialized!"))
            self._db_initialized = True
            self.completeChanged.emit()

        def init_failed(msg):
            self.label_initialize_msg.setText(self.tr("Failed to initialize database! %s") % msg)
            self._db_initialized = False
            self.completeChanged.emit()

        self.progressBar_initialize.setValue(0)
        self.label_initialize_msg.setText(self.tr("Start initializing database ..."))
        worker = DBInitializeWorker()
        worker.finished.connect(init_finished)
        worker.progress.connect(pg_callbk)
        worker.failed.connect(init_failed)
        worker.finished.connect(self.qthread.quit)
        worker.moveToThread(self.qthread)
        self.qthread.started.connect(worker.do_initialize)
        self.qthread.finished.connect(worker.deleteLater)
        self.qthread.start()

    def isComplete(self):
        return self._db_initialized

    def initializePage(self):
        if not self._db_initialized:
            self.do_db_initialize()

如上面的代码所示，DBInitializeWorker在调用thread.start（）之后永远不会运行。任何人都可以帮忙吗？感谢。