Geographic Information Systems Asked by Taher Alkamel on October 26, 2020
I am trying to run gdal:polygonize as a background task, but I am getting QGIS crashing and giving me this error:
QGIS died on signal 11ptrace: Operation not permitted.
No thread selected
No stack.
gdb returned 256
Aborted (core dumped)
How can I go around debugging this?
this is the code for my plugin’s module:
def polygonise(inputPath, outputPath, style=None):
task = processingTask(inputPath, outputPath, style)
QgsApplication.taskManager().addTask(task)
class processingTask(QgsTask):
def __init__(self, inputPath, outputPath, style=None):
QgsTask.__init__(self, "Publish layers")
self.inputPath = inputPath
self.outputPath = outputPath
self.style = style
self.exception = None
self.errortrace = None
def canCancel(self):
return False
def run(self):
try:
print("start processing")
processing.run('gdal:polygonize', {'INPUT':self.inputPath,'BAND':1,'FIELD':'DN','EIGHT_CONNECTEDNESS':False,'OUTPUT':self.outputPath})
print("stop processing2")
layer = QgsVectorLayer(self.outputPath, "{}_vectorised".format(self.inputPath.name()), "ogr")
QgsProject.instance().addMapLayer(layer)
if not layer.isValid():
print("Layer failed to load!")
if not (self.style == None):
categorizedStyling(layer, 'DN', self.style)
return layer
except Exception as e:
self.exception = e
self.errortrace = traceback.format_exc()
return False
def finished(self, ok):
if ok:
print("Task is finished")
else:
print("Task has errors")
I have tried both methods (Extending QgsTask and Task from a processing algorithm) listed in the QGSTask documentation and both resulted in the same outcome.
$ qgis --version
QGIS 3.4.14-Madeira 'Madeira' (exported)
Try looking at the QgsProcessingAlgRunnerTask https://qgis.org/pyqgis/master/core/QgsProcessingAlgRunnerTask.html . That should do all this for you already.
Answered by ndawson on October 26, 2020
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