I am trying to write something similar to a PyPlot windowed renderer using PyQt5. The core idea is that this is not supposed to be a PyQt application that constantly runs, but instead runs only on demand to visualize computational results.
A related question suggests that the correct approach is to use only one QApplication instance; however, this will not work for my use-case (a GUI interface is optional, it is secondary to main functionality, and will be needed infrequently).
The main code is supposed to do some data crunching, launch this PyQt app, plot some figures, kill the window, do more data crunching, launch the PyQt app a second time, plot those new results, etc. etc. etc.
However, on the second launch of this app, it will always crash with a seg fault.
[1] 54413 segmentation fault python my-fake-script-name.py
What is going on here?
import sys
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QApplication
from PyQt5.QtWidgets import QMainWindow
from PyQt5.QtCore import QCoreApplication, QUrl
from PyQt5.QtWebEngineWidgets import QWebEngineView
from PyQt5.QtWebEngineWidgets import QWebEngineProfile
class MainWindowWeb(QMainWindow):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.tw_title = "TINerator"
self.browser = QWebEngineView()
self.browser.loadFinished.connect(self.onLoadFinished)
self.setCentralWidget(self.browser)
self.setWindowTitle(f"{self.tw_title} (Loading...)")
def setParams(
self, title: str = None, window_size: tuple = None, allow_resize: bool = False
):
if title:
self.tw_title = title
self.setWindowTitle(f"{title} (Loading...)")
if window_size:
self.resize(window_size[0], window_size[1])
if not allow_resize:
self.setFixedSize(self.width(), self.height())
def loadURL(self, url: str):
self.browser.load(QUrl(url))
def onLoadFinished(self):
self.setWindowTitle(self.tw_title)
def closeEvent(self, event):
self.setWindowTitle(f"{self.tw_title} (Closing...)")
self.browser.deleteLater()
self.browser.stop()
self.browser.destroy()
del self.browser
self.close()
QCoreApplication.quit()
def run_web_app(
url: str,
title: str = "Hi Stack Overflow",
width: int = 900,
height: int = 600,
allow_resize: bool = True,
):
qt_app = QtWidgets.QApplication.instance()
if qt_app is None:
qt_app = QApplication(sys.argv)
qt_app.setQuitOnLastWindowClosed(True)
window = MainWindowWeb()
window.setParams(
title=title, window_size=(width, height), allow_resize=allow_resize
)
window.loadURL(url) # <--- crashes here
window.show()
err = qt_app.exec_()
del window
del qt_app
return err
run_web_app()
# do stuff
run_web_app()
# do stuff
run_web_app()
