QgsTask does not starts after adding to the task manager

[qgib]

Author Name: Alexander Bruy (@alexbruy)
Original Redmine Issue: 19267
Affected QGIS version: 3.3(master)
Redmine category:python_bindings_/_sipify

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Seems adding tasks to the task manager from Python using

task = TestTask('my task', 10)
QgsApplication.taskManager().addTask(task)

works fine from Python console, but does not work from the QAction's slot.

Test plugin attached. Install and activate this plugin, run task from the menu "Plugins → Test → Test". Nothing happens, task does not started. Now open init.py and uncomment line 55 which just adds some dummy debug message to the log. Restart QGIS and run plugin again, task will be added and executed.

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• tasktest.zip (Alexander Bruy)

[qgib]

Author Name: Alexander Bruy (@alexbruy)

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There is also another issue — finished() is not executed (probably because Python object is garbage collected when out of scope). To test this uncomment lines 52-53 in the init.py and run plugin. After task completes mo messages will be added to the message log.

[qgib]

Author Name: Salvatore Larosa (@slarosa)

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Hi Alexander, I don't know if this is or not a bug, but I would have defined the application taskmanager on @init@ method of the testplugin. Code below works as expected.

class TestPlugin:
    def __init__(self, iface):
        self.iface = iface
        self.tm = QgsApplication.taskManager()

    def initGui(self):
        self.action = QAction('Test', self.iface.mainWindow())
        self.iface.addPluginToMenu('Test', self.action)
        self.action.triggered.connect(self.run)

    def unload(self):
        self.iface.removePluginMenu('Test', self.action)

    def run(self):
        task = TestTask('my task', 10)
        self.tm.addTask(task)

    def complete(self):
        QgsMessageLog.logMessage('Task finished')

    def error(self):
        QgsMessageLog.logMessage('Error occurred')
</code>

[qgib]

Author Name: Alexander Bruy (@alexbruy)

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• status_id was changed from Open to Closed