[PySide] QThread crash before emitting finished signal

[William Dias]

Ok. I've just seen that I can't do a moveToThread in a object that has a
parent. That's the first point I've fixed in my code.

Apart from that, my threads are being destroyed as photoWorker and
photoThread objects run out of scope. How can I prevent python from doing
this? Making them instance objects is not an option since every time my
program reenters the method where they are declared it spawns new threads.

Thanks,


2012/6/7 William Dias <william.dias at gmail.com>

> Thank you, Sebastian. I followed the procedures described in the document
> and it worked. But I have another question.
> Take a look at the code bellow:
>
> class PhotoWorker(QObject):
>
> photoStatus = Signal(str, str)
>
> @Slot()
> def work(self):
>  self.db = sqlite_database.SQLiteDatabase("db1")
> self.timer = QTimer()
>  self.timer.timeout.connect(self.__resendPhoto)
> logger.info("photo worker started")
>  self.timer.start(10000)
>
> @Slot()
> def __resendPhoto(self):
>  data = self.db.selectPhoto()
> if data != None:
>  self.filename = data[0]
> self.tags = data[1]
>  logger.info("trying to resend photo " + self.filename)
> status = sendPhoto(self.tags, self.filename)
>  self.photoStatus.emit(self.filename, status)
>
> And in a GUI class, I do the following:
>
> photoWorker = http_connection.PhotoWorker(self)
>  photoWorker.photoStatus.connect(self.photoStatus)
> photoThread = QThread()
>  photoWorker.moveToThread(photoThread)
> photoThread.start()
> QMetaObject.invokeMethod(photoWorker, "work", Qt.QueuedConnection)
>
> I realized that when I create the photoWorker object, if I don't set its
> parent to self, my thread dies. Is this because my photoWorker doesn't have
> its own event loop? I am bit confused here. How should I proceed?
>
> Thank you.
>
> 2012/6/7 Sebastian Elner <sebastian at risefx.com>
>
>>  Although it is in the documentation, QThread is not meant to be used
>> this way (subclassing). Have a look at this:
>> http://labs.qt.nokia.com/2010/06/17/youre-doing-it-wrong/ It helped me a
>> lot. Also a complete stripped down example would greatly help in a case of
>> a segfault.
>>
>>
>>
>> On 06/07/2012 09:59 AM, William Dias wrote:
>>
>> Hi,
>>
>>  I have a subclass of QThread which uploads pictures to a webserver. For
>> each new picture created in the main thread, the program spawns a new
>> thread to handle the job. I've override the __init__ method to be able to
>> pass some parameters to the thread object, as you can see bellow.
>>
>>  class PhotoConnection(QThread):
>>>  photoStatus = Signal(str, str)
>>
>>  def __init__(self, tags, filename, parent=None):
>>>  QThread.__init__(self, parent)
>>>  self.tags = tags
>>>  self.filename = filename
>>
>>  def run(self):
>>>  status = sendPhoto(self.tags, self.filename)
>>>  self.photoStatus.emit(self.filename, status)
>>
>>
>>  In the GUI thread, the method responsible dor creating the threads is
>> the following:
>>
>>  def sendPhoto(self):
>>>  photoConnection = PhotoConnection(self.tags_to_string, self.filename,
>>> self)
>>>  photoConnection.photoStatus.connect(self.photoStatus)
>>>  photoConnection.finished.connect(self.threadFinished)
>>>  photoConnection.start()
>>>
>>
>>  In the PhotoConnection, if I don't set the parent of my Qthread object
>> to self (for example, if I set to None) or if I don't override the __init__
>> method and create another method to pass the arguments, when the thread
>> finishes the execution I got a segfault.
>> Why is this happening? Can you help me?
>>
>>  Thanks,
>>
>>
>> _______________________________________________
>> PySide mailing listPySide at qt-project.orghttp://lists.qt-project.org/mailman/listinfo/pyside
>>
>>
>>
>> --
>> Sebastian Elsner    -    pipeline td   -   r i s e |  fx
>>
>> t:  +49 30 20180300                 sebastian at risefx.com
>>                                           www.risefx.com
>>
>> r i s e |  fx  GmbH
>> Schlesische Strasse 28 Aufgang B, 10997 Berlin
>> Geschäftsführer: Sven Pannicke, Robert Pinnow
>>
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>>
>>
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>>
>>
>
>
> --
> William Marques Dias
>



-- 
William Dias
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