[FIXED] PySide - QThread running but not entering slot connected to signal 'started'

Issue

I thought I've read it all about threading in Qt, but apparently I'm getting it wrong. I'm stuck with this stuff for some time now, so I would really appreciate your help a lot.

So, I created a class that starts a thread in its __init__ method:

class MyClass(object):
    def __init__(self):
        (...)

        self.thread = QtCore.QThread(parent)
        worker = Worker()
        QtCore.QObject.connect(self.thread, QtCore.SIGNAL('started()'), worker,
                QtCore.SLOT('doWork()'))
        QtCore.QObject.connect(worker, QtCore.SIGNAL('finished()'), self.thread,
                QtCore.SLOT('quit()'))
        QtCore.QObject.connect(worker, QtCore.SIGNAL('finished()'), worker,
                QtCore.SLOT('deleteLater()'))
        QtCore.QObject.connect(self.thread, QtCore.SIGNAL('finished()'),
                self.thread, QtCore.SLOT('deleteLater()'))
        worker.moveToThread(self.thread)
        self.thread.start()

Worker class looks like that:

class Worker(QtCore.QObject):
    (some signals)

    def doWork(self):
        print "doing my work"

The problem is that my doWork slot is never executed, although the thread is running.

After creating instance of MyClass, let's say: obj = MyClass()

I can call: obj.thread.isRunning()

which returns True.

I assume that signal 'started' is not emitted, because of instantly exiting the method where thread was created (when I add sleep after starting thread, it enters doWork slot). I wonder how such situation should be handled properly.

Please let me know if I did not explain my problem clearly. Thank you all for help in advance.

Solution

Your worker is being garbage collected after the MyClass constructor returns. Make worker a member of MyClass so that it persists beyond the constructor.

self.worker = Worker()

Answered By - user3419537