[英]Python - PyQt: Memory issue with QThread
我想建立一个Qt界面来控制摄像机的采集。
我想要的是:在进行硬件通信之前,我正在测试一个控制“伪相机”的GUI,该GUI是一个连续的循环,如果启动该循环,则每100毫秒给出一个随机图像。 图像采集在单独的线程中运行,以便用户可以与GUI进行交互。 用户可以通过按钮开始和停止采集。
我要如何做:我的第一次尝试是简单地对QThread
进行tanzi,然后调用run()
方法,该方法将包含一个无限循环,其中单个图像采集由QThread.sleep(0.1)
交错。 我注意到在停止并重新启动线程后,该程序开始滞后并在一段时间后崩溃。 通过阅读一些Qt主页和周围的文章,然后我了解到,做我想做的最好的方法是:
子类化
QObject
以创建工作器。 实例化此worker对象和QThread
。 将工作程序移动到新线程。
此外,在之后的想法这个帖子,我添加了一个QTimer
对象无限期循环的线程内的工作人员,我实现一个active
标志,只是让线程运行,如果没有它设置为做任何False
。 这种解决方案似乎在一开始就起作用。 我可以根据需要多次启动,停止和重新开始采集。
问题:
1)当摄像头无法获取时,CPU总是占用相当多的资源(根据Windows任务管理器,在我看来,这是大约30%)。
2)有时,开始获取后,内存开始被填充,就像每个新映像都被分配到新内存中一样(我想应该是将其覆盖),直到程序变得无响应然后崩溃。 下图是发生这种情况时在任务管理器中看到的图像: 红色箭头对应于采集开始的时间。
我在哪里做错了? 这是正确的前进方法吗?
编码
from PyQt5 import QtCore, QtWidgets
import sys
import numpy as np
import matplotlib
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg
class MyWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle('MyWindow')
self._main = QtWidgets.QWidget()
self.setCentralWidget(self._main)
# generate matplotlib canvas
self.fig = matplotlib.figure.Figure(figsize=(4,4))
self.canvas = FigureCanvasQTAgg(self.fig)
self.ax = self.fig.add_subplot(1,1,1)
self.im = self.ax.imshow(np.zeros((1000, 1000)), cmap='viridis')
self.im.set_clim(vmin=0,vmax=1)
self.canvas.draw()
# Add widgets and build layout
self.startcambutton = QtWidgets.QPushButton('Start', checkable=True)
self.startcambutton.released.connect(self.acquire)
self.contincheck = QtWidgets.QCheckBox("Continuous")
self.contincheck.clicked.connect(self.continuous_acquisition)
self.contincheck.setChecked(True)
layout = QtWidgets.QGridLayout(self._main)
layout.addWidget(self.canvas, 0, 0)
layout.addWidget(self.startcambutton, 1, 0)
layout.addWidget(self.contincheck, 2, 0)
# Initialize worker and timer and moveToThread
self.fake_camera_thread = QtCore.QThread()
self.fake_camera_timer = QtCore.QTimer()
self.fake_camera_timer.setInterval(0)
self.fake_camera_worker = FakeCamera(self)
self.fake_camera_worker.moveToThread(self.fake_camera_thread)
self.fake_camera_timer.timeout.connect(self.fake_camera_worker.acquire)
self.fake_camera_thread.started.connect(self.fake_camera_timer.start)
self.fake_camera_thread.finished.connect(self.fake_camera_worker.deleteLater)
self.fake_camera_thread.finished.connect(self.fake_camera_timer.deleteLater)
self.fake_camera_thread.finished.connect(self.fake_camera_thread.deleteLater)
self.fake_camera_thread.start()
self.camera_thread = self.fake_camera_thread
self.camera = self.fake_camera_worker
self.camera.image.connect(self.image_acquired)
def continuous_acquisition(self):
if self.contincheck.isChecked(): self.startcambutton.setCheckable(True)
else: self.startcambutton.setCheckable(False)
def acquire(self):
if self.startcambutton.isCheckable() and not self.startcambutton.isChecked():
self.startcambutton.setText('Start')
self.contincheck.setEnabled(True)
elif self.startcambutton.isCheckable() and self.startcambutton.isChecked():
self.startcambutton.setText('Stop')
self.contincheck.setDisabled(True)
self.camera.toggle()
@QtCore.pyqtSlot(object)
def image_acquired(self, image):
self.im.set_data(image)
self.canvas.draw()
def closeEvent(self, event):
""" If window is closed """
self.closeApp()
event.accept() # let the window close
def closeApp(self):
""" close program """
self.camera_thread.quit()
self.camera_thread.wait()
self.close()
return
class FakeCamera(QtCore.QObject):
image = QtCore.pyqtSignal(object)
def __init__(self, parent):
QtCore.QObject.__init__(self)
self.parent = parent
self.active = False
def toggle(self):
self.active = not self.active
def acquire(self):
""" this is the method running indefinitly in the associated thread """
if self.active:
self.new_acquisition()
def new_acquisition(self):
noise = np.random.normal(0, 1, (1000, 1000))
self.image.emit(noise)
if not self.parent.startcambutton.isChecked():
self.active = False
QtCore.QThread.sleep(0.1)
if __name__ == '__main__':
app = QtCore.QCoreApplication.instance()
if app is None:
app = QtWidgets.QApplication(sys.argv)
mainGui = MyWindow()
mainGui.show()
app.aboutToQuit.connect(app.deleteLater)
app.exec_()
QThread.sleep()
仅接受整个参数,当传递一个浮点数时,它将对其进行四舍五入,在您的情况下,该值将被四舍五入为0,因此没有暂停,因此将连续发出信号,但是绘画需要一段时间,所以数据将存储在队列中,因为它增加了内存。 另一方面,如果QTimer
要连续调用任务,则最好将其驻留在处理任务的对象的线程中,这样QTimer
就是FakeCamera的儿子就足够了。 另一个改进是装饰器@QtCore.pyqtSlot()
的使用,因为连接是用C ++给出的,因此效率更高。 最后,我改进了设计,因为FakeCamera
不应直接与GUI交互,因为如果要与另一个GUI一起使用,则必须修改很多代码,而创建插槽更好。
from PyQt5 import QtCore, QtWidgets
import numpy as np
import matplotlib
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg
class MyWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle('MyWindow')
self._main = QtWidgets.QWidget()
self.setCentralWidget(self._main)
# generate matplotlib canvas
self.fig = matplotlib.figure.Figure(figsize=(4,4))
self.canvas = FigureCanvasQTAgg(self.fig)
self.ax = self.fig.add_subplot(1,1,1)
self.im = self.ax.imshow(np.zeros((1000, 1000)), cmap='viridis')
self.im.set_clim(vmin=0,vmax=1)
self.canvas.draw()
# Add widgets and build layout
self.startcambutton = QtWidgets.QPushButton('Start', checkable=True)
self.startcambutton.released.connect(self.acquire)
self.contincheck = QtWidgets.QCheckBox("Continuous")
self.contincheck.toggled.connect(self.startcambutton.setCheckable)
self.contincheck.setChecked(True)
layout = QtWidgets.QGridLayout(self._main)
layout.addWidget(self.canvas, 0, 0)
layout.addWidget(self.startcambutton, 1, 0)
layout.addWidget(self.contincheck, 2, 0)
# Initialize worker and timer and moveToThread
fake_camera_thread = QtCore.QThread(self)
self.fake_camera_worker = FakeCamera()
self.fake_camera_worker.moveToThread(fake_camera_thread)
self.startcambutton.toggled.connect(self.fake_camera_worker.setState)
self.fake_camera_worker.image.connect(self.image_acquired)
fake_camera_thread.started.connect(self.fake_camera_worker.start)
fake_camera_thread.finished.connect(self.fake_camera_worker.deleteLater)
fake_camera_thread.finished.connect(fake_camera_thread.deleteLater)
fake_camera_thread.start()
@QtCore.pyqtSlot()
def acquire(self):
if self.startcambutton.isCheckable():
text = "Stop" if self.startcambutton.isChecked() else "Start"
self.startcambutton.setText(text)
self.contincheck.setEnabled(not self.startcambutton.isChecked())
@QtCore.pyqtSlot(object)
def image_acquired(self, image):
self.im.set_data(image)
self.canvas.draw()
class FakeCamera(QtCore.QObject):
image = QtCore.pyqtSignal(object)
def __init__(self, parent=None):
super(FakeCamera, self).__init__(parent)
self.active = False
self.fake_camera_timer = QtCore.QTimer(self, interval=0)
self.fake_camera_timer.timeout.connect(self.acquire)
@QtCore.pyqtSlot()
def start(self):
self.fake_camera_timer.start()
@QtCore.pyqtSlot(bool)
def setState(self, state):
self.active = state
@QtCore.pyqtSlot()
def toggle(self):
self.active = not self.active
@QtCore.pyqtSlot()
def acquire(self):
""" this is the method running indefinitly in the associated thread """
if self.active:
self.new_acquisition()
QtCore.QThread.msleep(100)
def new_acquisition(self):
noise = np.random.normal(0, 1, (1000, 1000))
self.image.emit(noise)
if __name__ == '__main__':
import sys
app = QtCore.QCoreApplication.instance()
if app is None:
app = QtWidgets.QApplication(sys.argv)
mainGui = MyWindow()
mainGui.show()
app.aboutToQuit.connect(app.deleteLater)
sys.exit(app.exec_())
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