Occasionally get "QThread: Destroyed while thread is still running" when running multiple threads

[JonB]

@gunraidan
You have to read the Qt QJson... classes documentation and write the code. Btw did you try to see if your pokemon_dict["abilities"][0]['ability']['name'] works?

From Python you might be more comfortable getting the json module working. It may integrate more smoothly in Python than the Qt one, if the Qt one doesn't work with your pokemon_dict["abilities"][0]['ability']['name'].

[gunraidan]

@JonB said in Occasionally get "QThread: Destroyed while thread is still running" when running multiple threads:

@gunraidan
You have to read the Qt QJson... classes documentation and write the code. Btw did you try to see if your pokemon_dict["abilities"][0]['ability']['name'] works?

From Python you might be more comfortable getting the json module working. It may integrate more smoothly in Python than the Qt one, if the Qt one doesn't work with your pokemon_dict["abilities"][0]['ability']['name'].

This is embarrassing but I just realized I quoted you before without putting my code in.
It strongly gives the impression I'm not putting in the effort, which I don't think is accurate.

I came up with the following code:

    def handle_request(self, reply):
        er = reply.error()
        
        if er == QtNetwork.QNetworkReply.NetworkError.NoError:

            bytes_string = reply.readAll()
            pokemon_dict = json.loads(bytes_string)
            x = QByteArray(pokemon_dict["abilities"][0]['ability']['name'])
            print(x)

In my head the json.loads will load the response into json format and then x will result in that part of the code being transferred to bytes so Python can read it.

However, I still get the same error:

Traceback (most recent call last):
  File "c:\Users\Nader\OneDrive\Documents\Coding\Python\TestNetwork.py", line 44, in handle_request
    bytes_string = json.loads(reply.readAll())
  File "C:\Users\Nader\AppData\Local\Programs\Python\Python310\lib\json\__init__.py", line 339, in loads
    raise TypeError(f'the JSON object must be str, bytes or bytearray, '
TypeError: the JSON object must be str, bytes or bytearray, not QByteArray

I have gone to the documentation here, but it lists simply the function and no examples of QJson in use (outside of a saved game load which isn't much like I'm doing.)

[JonB]

@gunraidan said in Occasionally get "QThread: Destroyed while thread is still running" when running multiple threads:

I have gone to the documentation here, but it lists simply the function and no examples of QJson in use (outside of a saved game load which isn't much like I'm doing.)

Well, that's all you get!

You have attempted to change your code in the light of the error, but unfortunately not the right thing! Please read the message carefully. First:

File "c:\Users\Nader\OneDrive\Documents\Coding\Python\TestNetwork.py", line 44, in handle_request

bytes_string = json.loads(reply.readAll())

Since that clearly shows bytes_string = json.loads(reply.readAll()) while you claim your code has pokemon_dict = json.loads(bytes_string), how can you get that error message from the code you show? I can only conclude that is not the code you have to cause that message. Please don't do this, it makes it very frustrating when people try to help and code/messages are not actually what you claim they are.

Second:

File "C:\Users\Nader\AppData\Local\Programs\Python\Python310\lib\json_init_.py", line 339, in loads

raise TypeError(f'the JSON object must be str, bytes or bytearray, '

TypeError: the JSON object must be str, bytes or bytearray, not QByteArray

Read the error message. It tells you it was in the json.loads(something) call. It tells you it requires the parameter to be "str, bytes or bytearray", but that it is actually "QByteArray" (as returned from readAll()). And it is apparently not prepared to convert for you. Hence I wrote earlier:

TypeError: the JSON object must be str, bytes or bytearray, not QByteArray

Then you need to convert Qt QByteArray to bytes/bytearray, however you do that from PyQt6.

You were supposed to Google to find out how to do that. I don't, I don't use Python. Your putting in x = QByteArray(...) after the json.loads() call is not going to address this, you need to change what you pass to json.loads().

I will have a go at producing something in next post.....

[JonB]

@gunraidan
Here is the code (tested PyQt5) for the two possible approaches:

import json

from PyQt5 import QtCore

if __name__ == '__main__':
    # I put your sample JSON into a file, since they are not arriving at my serial port
    f = QtCore.QFile("file.json")
    if not f.open(QtCore.QIODevice.ReadOnly):
        raise "Whoops"
    # following line's `readAll()` returns `QByteArray` type, just like when you read from serial port
    qbytearray = f.readAll()
    f.close()

    # Use `json.loads()` approach:
    # next line converts Qt `QByteArray` type to Python `bytes` type...
    pythonbytearray = bytes(qbytearray)
    # ...so that now it is acceptable to `json.loads(...)`
    pokemon_dict = json.loads(pythonbytearray)
    x = pokemon_dict["abilities"][0]['ability']['name']
    # next line prints `static`, which must be the value there
    print(x)

    # Use `QtCore.QJson...` approach:
    pokemon_dict = QtCore.QJsonDocument.fromJson(qbytearray)
    x = pokemon_dict["abilities"][0]['ability']['name'].toString()
    # next line prints `static`, which must be the value there
    print(x)

As you can see, all you had to discover for Python/PyQt json.loads(...) is that you can convert a Qt QByteArray to a Python bytes array via bytes(qByteArrayValue).

Use either one of these approaches. The json modules is slightly better integrated into Python than the Qt QJson... classes (e.g. note the QJson expression requires the toString() at the end, but the json one does not), so you may prefer to use the former. On the other hand, while json.loads() requires converting a QByteArray to a bytes, QJsonDocument.fromJson() does not.

[gunraidan]

@JonB said in Occasionally get "QThread: Destroyed while thread is still running" when running multiple threads:

@gunraidan
Here is the code (tested PyQt5) for the two possible approaches:

import json

from PyQt5 import QtCore

if __name__ == '__main__':
    # I put your sample JSON into a file, since they are not arriving at my serial port
    f = QtCore.QFile("file.json")
    if not f.open(QtCore.QIODevice.ReadOnly):
        raise "Whoops"
    # following line's `readAll()` returns `QByteArray` type, just like when you read from serial port
    qbytearray = f.readAll()
    f.close()

    # Use `json.loads()` approach:
    # next line converts Qt `QByteArray` type to Python `bytes` type...
    pythonbytearray = bytes(qbytearray)
    # ...so that now it is acceptable to `json.loads(...)`
    pokemon_dict = json.loads(pythonbytearray)
    x = pokemon_dict["abilities"][0]['ability']['name']
    # next line prints `static`, which must be the value there
    print(x)

    # Use `QtCore.QJson...` approach:
    pokemon_dict = QtCore.QJsonDocument.fromJson(qbytearray)
    x = pokemon_dict["abilities"][0]['ability']['name'].toString()
    # next line prints `static`, which must be the value there
    print(x)

As you can see, all you had to discover for Python/PyQt json.loads(...) is that you can convert a Qt QByteArray to a Python bytes array via bytes(qByteArrayValue).

Use either one of these approaches. The json modules is slightly better integrated into Python than the Qt QJson... classes (e.g. note the QJson expression requires the toString() at the end, but the json one does not), so you may prefer to use the former. On the other hand, while json.loads() requires converting a QByteArray to a bytes, QJsonDocument.fromJson() does not.

Thank you.

The following code:

pokemon_dict = []
json2qt = QtCore.QJsonDocument.fromJson

class MainWindow(QWidget):  
    def __init__ (self):
        super().__init__()
        self.title = "Window"
        self.left = 200
        self.top = 300
        self.width = 300
        self.height = 300
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top,self.width, self.height)

        self.start_button()
        self.show()
        
    def start_button(self):
        self.s_button = QtWidgets.QPushButton(self)
        self.s_button.setText('Start')
        self.s_button.clicked.connect(self.site_request)
        
    
    def site_request(self):
        url = 'https://pokeapi.co/api/v2/pokemon/pikachu'
        req = QtNetwork.QNetworkRequest(QUrl(url))
        
        self.nam = QtNetwork.QNetworkAccessManager()
        self.nam.finished.connect(self.handle_request)
        self.nam.get(req)
        
    def handle_request(self, reply):
        er = reply.error()
        
        if er == QtNetwork.QNetworkReply.NetworkError.NoError:
            qbyte = reply.readAll()
            pokemon_dict = json2qt(qbyte)
            x = pokemon_dict["abilities"][0]['ability']['name'].toString()
            print(x)
        else:
            print ("Error")
            print(reply.errorString())
        
        
if __name__ == '__main__':        
    app = QApplication(sys.argv) 
    ex = MainWindow()        
    code = app.exec()
    sys.exit(code)

Works as it prints the name: "static".

Thank you for all your help!

One more thing, that you don't have to answer. Do you have any idea what the qt.tlsbackend.ossl: Failed to load libssl/libcrypto. could be? It doesn't effect the program at all and I assume has to do with the api's security not being picked up since it references "ssl"?

Doing some research of what "libssl and libcrypto are took me to this page.

[jsulm]

@gunraidan said in Occasionally get "QThread: Destroyed while thread is still running" when running multiple threads:

libssl/libcrypto

It's the OpenSSL library which is needed if you want to access https URLs.

[gunraidan]

@jsulm said in Occasionally get "QThread: Destroyed while thread is still running" when running multiple threads:

OpenSSL library

I followed the directions here to go to this site and download the installer for Windows.

I still get the error though. :(

[jsulm]

@gunraidan You should rather install OpenSSL through Qt installer/maintenance tool. See https://stackoverflow.com/questions/68624474/how-to-deploy-qt-application-with-openssl

Also, this is only an issue if you want to access HTTPS URLs. For HTTP you do not need OpenSSL.

[gunraidan]

I'm not sure if I should make a new thread or not, so I'll just post this here.

I can't get self.d_name to print after the api function has been called:

from PyQt6 import QtNetwork
from PyQt6 import QtCore
from PyQt6.QtCore import QUrl
from PyQt6.QtGui import*
from PyQt6 import QtWidgets
from PyQt6.QtWidgets import*
import sys

json2qt = QtCore.QJsonDocument.fromJson

class MainWindow(QWidget):  
    def __init__ (self):
        super().__init__()
        self.title = "Window"
        self.left = 200
        self.top = 300
        self.width = 300
        self.height = 300
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top,self.width, self.height)
        self.start_button()
        self.show()
        
    def start_button(self):
        self.s_button = QtWidgets.QPushButton(self)
        self.s_button.setText('Start')
        self.s_button.clicked.connect(self.site_request)
        
    
    def site_request(self):
        url = 'https://pokeapi.co/api/v2/pokemon/pikachu'
        req = QtNetwork.QNetworkRequest(QUrl(url))
        
        self.nam = QtNetwork.QNetworkAccessManager()
        self.nam.finished.connect(self.handle_request)
        self.nam.get(req)
        
    def handle_request(self, reply):
        er = reply.error()
        if er == QtNetwork.QNetworkReply.NetworkError.NoError:
            qbyte = reply.readAll()
            pokemon_dict = json2qt(qbyte)
            self.d_name = pokemon_dict["abilities"][0]['ability']['name'].toString()
        else:
            print ("Error")
            print(reply.errorString())
            
    def get_all(self):
        self.site_request()
        print(self.d_name)

if __name__ == '__main__':        
    app = QApplication(sys.argv) 
    ex = MainWindow()        
    code = app.exec()
    sys.exit(code)

However, when I put self.d_name to print here:

  def handle_request(self, reply):
        er = reply.error()
        if er == QtNetwork.QNetworkReply.NetworkError.NoError:
            qbyte = reply.readAll()
            pokemon_dict = json2qt(qbyte)
            self.d_name = pokemon_dict["abilities"][0]['ability']['name'].toString()
            print (self.d_name)
        else:
            print ("Error")
            print(reply.errorString())

It prints out fine.

It should print out either way, it's a "self variable".

Anyone know what I'm doing wrong?

[JonB]

@gunraidan
It won't be about self (that bit is fine), it will be about when you try to print the value.

Firstly, you have print(self.d_name) inside a method get_all(). But since your code never actually calls get_all()....

Even if you did call it. site_request()calls self.nam.get(req). But QNetworkAccessManager.get() only initiates a GET request. It does not wait for it to complete and return. Only when finished signal is received and handle_request() is called does self.d_name = ... get executed. That happens asynchronously at a later time. So trying to access it immediately after calling site_request() is too early.