Merge pull request #4615 from ales-erjavec/fixes/test-learners-segfault

[FIX] owtestandscore: Add cancelled tasks to dispose queue

Author: janezd

Orange/widgets/evaluate/owtestandscore.py

@@ -20,7 +20,7 @@
 from AnyQt.QtCore import Qt, QSize, QThread
 from AnyQt.QtCore import pyqtSlot as Slot
 from AnyQt.QtGui import QStandardItem, QDoubleValidator
-from AnyQt.QtWidgets import QHeaderView, QTableWidget, QLabel
+from AnyQt.QtWidgets import QHeaderView, QTableWidget, QLabel, QApplication
 
 from Orange.base import Learner
 import Orange.classification
@@ -1085,6 +1085,8 @@ def cancel(self):
             task.cancel()
             task.progress_changed.disconnect(self.setProgressValue)
             task.watcher.finished.disconnect(self.__task_complete)
+            add_task_to_dispose_queue(task)
+
             self.progressBarFinished()
             self.setStatusMessage("")
 
@@ -1094,6 +1096,15 @@ def onDeleteWidget(self):
         super().onDeleteWidget()
 
 
+def add_task_to_dispose_queue(task: TaskState):
+    # transfer ownership of task to Qt, and delete it after completion
+    # all other signals from task should be disconnected.
+    assert task.parent() is None
+    app = QApplication.instance()
+    task.setParent(app)
+    task.watcher.finished.connect(task.deleteLater)
+
+
 class UserInterrupt(BaseException):
     """
     A BaseException subclass used for cooperative task/thread cancellation