H5 worker thread cannot be terminated at will

[leofang]

This is a follow-up of #26. The following code snippet was commented out because it would freeze the whole window:

ptycho_gui/nsls2ptycho/ptycho_gui.py

Lines 973 to 975 in 211041e

	#if self.roiWindow._worker_thread.isRunning():
	# self.roiWindow._worker_thread.terminate()
	# self.roiWindow._worker_thread.wait()

The offending call is thread.terminate(). As a result, currently during batch processing if one clicks "Stop", the H5 worker will still finish up the work in the background. Only the whole processing queue is killed.

If a more recent Qt/PyQt5 is available (at least 5.10) we should revisit this problem. I suspect it's the underlying implementation causing the problem.

[leofang]

Need to ask Anaconda folks to update Qt/PyQt: ContinuumIO/anaconda-issues#9124

[leofang]

If a more recent Qt/PyQt5 is available (at least 5.10) we should revisit this problem. I suspect it's the underlying implementation causing the problem.

It's probably not this reason. Tried building PyQt 5.12.3 (conda-forge/pyqt-feedstock#61) on top of condo-forge's new Qt 5.12.1 (conda-forge/qt-feedstock#110). Still hangs. I probably used thread.terminate() wrong, but I still can't figure out why...

[tacaswell]

What is the type of HardWorker?

[leofang]

It inherits from QThread and its run method is overridden:

ptycho_gui/nsls2ptycho/core/ptycho_recon.py

Lines 197 to 222 in 211041e

	# a worker that does the rest of hard work for us
	class HardWorker(QtCore.QThread):
	update_signal = QtCore.pyqtSignal(int, object) # connect to MainWindow???
	def __init__(self, task=None, *args, parent=None):
	super().__init__(parent)
	self.task = task
	self.args = args
	self.exception_handler = None
	#self.update_signal = QtCore.pyqtSignal(int, object) # connect to MainWindow???
	def run(self):
	try:
	if self.task == "save_h5":
	self._save_h5(self.update_signal.emit)
	elif self.task == "fetch_data":
	self._fetch_data(self.update_signal.emit)
	# TODO: put other heavy lifting works here
	# TODO: consider merge other worker threads to this one?
	except ValueError as ex:
	# from _fetch_data(), print it and quit
	print(ex, file=sys.stderr)
	print("[ERROR] possible reason: no image available for the selected detector/scan", file=sys.stderr)
	except Exception as ex:
	# use MainWindow's exception handler
	if self.exception_handler is not None:
	self.exception_handler(ex)