qt5reactor_threads.py

import qt5reactor
import sys
import time
import twisted

from PyQt5 import QtCore


def thread():
    print('threading')
    time.sleep(1)
    print('done threading')


def quit():
    print('quitting')

    # TODO: _stopThreadPool() should not be necessary but otherwise
    #       it hangs on quit.  Killing results in:
    #
    # Exception ignored in: <module 'threading' from '/usr/lib/python3.5/threading.py'>
    # Traceback (most recent call last):
    #   File "/usr/lib/python3.5/threading.py", line 1288, in _shutdown
    #     t.join()
    #   File "/usr/lib/python3.5/threading.py", line 1054, in join
    #     self._wait_for_tstate_lock()
    #   File "/usr/lib/python3.5/threading.py", line 1070, in _wait_for_tstate_lock
    #     elif lock.acquire(block, timeout):
    # KeyboardInterrupt

    twisted.internet.reactor._stopThreadPool()

    app.quit()
    print('already quit')


app = QtCore.QCoreApplication(sys.argv)

qt5reactor.install()

# TODO: getThreadPool().start() should not be required but otherwise
#       it hangs without running thread()
twisted.internet.reactor.getThreadPool().start()

d = twisted.internet.threads.deferToThread(thread)
d.addCallback(lambda _: quit())

sys.exit(app.exec())

qt5reactor_threads_run.py

import qt5reactor
import sys
import time
import twisted

from PyQt5 import QtCore


def thread():
    print('threading')
    time.sleep(1)
    print('done threading')


def quit():
    print('quitting')

    app.quit()
    print('already quit')


app = QtCore.QCoreApplication(sys.argv)

qt5reactor.install()

d = twisted.internet.threads.deferToThread(thread)
d.addCallback(lambda _: quit())

import twisted.internet
sys.exit(twisted.internet.reactor.run())

twisted_threads.py

import sys
import time
import twisted.internet
import twisted.internet.reactor
import twisted.internet.threads


def thread():
    print('threading')
    time.sleep(1)
    print('done threading')


def quit():
    print('quitting')
    twisted.internet.reactor.stop()
    print('already quit')


d = twisted.internet.threads.deferToThread(thread)
d.addCallback(lambda _: quit())

sys.exit(twisted.internet.reactor.run())

Replacing
sys.exit(app.exec())
with
sys.exit(twisted.internet.reactor.run())
works for me, and I can kill the application with CRTL-C, however my "quit" menu item no longer works - even when I define quit and link it to my thread. It seems to get stuck on a thread.join() call from my Qt window.