<div dir="ltr"><div dir="ltr"><div dir="ltr">After some testing to dig deeper in the QThread subject, pushed by the previous related thread, I found something I don't really understand (just to add something more to the "you never stop learning").<div><br></div><div>Take the following simple example:</div><div><br></div><div><div><pre class="gmail-lang-py gmail-s-code-block" style="margin-top:0px;padding:12px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;line-height:1.30769;font-size:13px;vertical-align:baseline;box-sizing:inherit;width:auto;max-height:600px;overflow:auto;border-radius:5px;word-wrap:normal"><code class="gmail-hljs gmail-language-python" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit;background-color:transparent;white-space:inherit"><span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">from</span> PyQt5 <span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">import</span> QtCore, QtWidgets

<span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">class</span> <span class="gmail-hljs-title gmail-class_" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">Worker</span>(QtCore.QThread):
    <span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">def</span> <span class="gmail-hljs-title gmail-function_" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">run</span>(<span class="gmail-hljs-params" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">self</span>):
        <span class="gmail-hljs-built_in" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">super</span>().run()


<span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">class</span> <span class="gmail-hljs-title gmail-class_" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">Test</span>(QtWidgets.QWidget):
    <span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">def</span> __init__(self):
        <span class="gmail-hljs-built_in" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">super</span>().__init__()
        layout = QtWidgets.QVBoxLayout(self)
        self.button = QtWidgets.QPushButton(<span class="gmail-hljs-string" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">'start'</span>)
        layout.addWidget(self.button)
        self.label = QtWidgets.QLabel(<span class="gmail-hljs-string" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">'waiting'</span>)
        layout.addWidget(self.label)

        self.worker = Worker()

        self.button.clicked.connect(self.start)

    <span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">def</span> <span class="gmail-hljs-title gmail-function_" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">start</span>(<span class="gmail-hljs-params" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">self</span>):
        self.label.setText(<span class="gmail-hljs-string" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">'started'</span>)
        self.button.setEnabled(<span class="gmail-hljs-literal" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">False</span>)
        self.worker.start()

<span class="gmail-hljs-keyword" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;box-sizing:inherit">import</span> sys
app = QtWidgets.QApplication(sys.argv)
w = Test()
w.show()
sys.exit(app.exec_())</code></pre></div><div><br></div><div>This results in freezing the whole application as soon as the thread is started.</div><div>Why does this happen? I believe it could be related to how threading works and the whole wrapping, but I'm not sure and I'd like to understand the reason for this anyway.</div><div><br>If instead of calling run() I call exec() (which is what run() actually does), it works fine.</div><div><br></div>-- <br><div dir="ltr" class="gmail_signature">È difficile avere una convinzione precisa quando si parla delle ragioni del cuore. - "Sostiene Pereira", Antonio Tabucchi<br><a href="http://www.jidesk.net" target="_blank">http://www.jidesk.net</a></div></div></div></div></div>