PySide QtCore.QThreadPool and QApplication.quit() causes hangs? - multithreading

Question

I want to use Qt's QThreadPool, but it seems to be hanging my application if the workers in the queue do not finish before calling QApplication.quit(). Can anyone tell me if i'm doing something wrong in the reduced testcase below?
import logging
log = logging.getLogger(__name__)
import sys
from PySide import QtCore
import time
class SomeWork(QtCore.QRunnable):
def __init__(self, sleepTime=1):
super(SomeWork, self).__init__()
self.sleepTime = sleepTime
def run(self):
time.sleep(self.sleepTime)
print "work", QtCore.QThread.currentThreadId()
def _test(argv):
logging.basicConfig(level=logging.NOTSET)
app = QtCore.QCoreApplication(argv)
pool = QtCore.QThreadPool.globalInstance()
TASK_COUNT = int(argv[1]) if len(argv) > 1 else 1
mainThread = QtCore.QThread.currentThreadId()
print "Main thread: %s"%(mainThread)
print "Max thread count: %s"%(pool.maxThreadCount())
print "Work count: %s"%(TASK_COUNT)
for i in range(TASK_COUNT):
pool.start(SomeWork(1))
def boom():
print "boom(); calling app.quit()"
app.quit()
QtCore.QTimer.singleShot(2000, boom)
#import signal
#signal.signal(signal.SIGINT, signal.SIG_DFL)
return app.exec_()
if __name__ == '__main__':
sys.exit(_test(sys.argv))
To be clear, this is the output I get:
(env)root#localhost:# python test_pool.py 1
Main thread: 3074382624
Max thread count: 1
Work count: 1
work 3061717872
boom(); calling app.quit()
(env)root#workshop:/home/workshop/workshop/workshop# python test_pool.py 20
Main thread: 3074513696
Max thread count: 1
Work count: 20
work 3060783984
boom(); calling app.quit()
And it hangs forever on the second command, but not the first.
Thanks for any help you may have.
EDIT:
To be clear, I expect that if app.quit() is called while threads are in the thread queue, they do not run. Already running threads should run to completion. Then, the application should close.
This example fails on a Windows machine as well
This example works on the same Windows machine, but using PyQt4

Answer 1

Adding this to _test() just before the exec() fixes the issue, although all the threads run:
def waitForThreads():
print "Waiting for thread pool"
pool.waitForDone()
app.aboutToQuit.connect(waitForThreads)