(Synchronous) Thread Control

[Olivier Parisy]

Hi,

I like to use thread to simplify the handling of independant,
blocking tasks. But controling them from a main thread is
not always easy to do in a clean way. So I've written some
generic code whose purpose is to start and stop threads in
a synchronous (blocking) way from the caller's point of view.

Hence, after start() is called you are garanteed that the
thread is running, and after stop() you know it has completed
its tasks.

At the end of this message, you'll find an example of the kind
of code I'm using. Here is its output :

Thread: starting
Main: waiting 5 seconds
Thread: beating
Thread: beating
Thread: beating
Thread: beating
Main: done sleeping, stopping thread
Wrapper: joining thread
Thread: beating
Thread: exiting


It seems like the main thread never exits from join(), in spite of
the timeout and the likeliness of the sub thread ending.

Any idea of what I've done wrong?

Best regards,
Olivier.



import threading, time

class IntThread:

def start(self):
launched = threading.Event() # Initially false
self.listener = self.Listener(launched)
self.listener.start()
launched.wait()

def stop(self):
self.listener.stop()
print "Wrapper: joining thread"
self.listener.join(5) # Should be more than enought
print "Wrapper: after join()"

class Listener(threading.Thread):

def __init__(self, event):
threading.Thread.__init__(self)
self.do_stop = False
self.event = event

def stop(self):
self.do_stop = True

def run(self):
print "Thread: starting"
self.event.set()
while not self.do_stop:
time.sleep(1)
print "Thread: beating"
print "Thread: exiting"

def test():
thd = IntThread()
thd.start()
delay = 5
print "Main: waiting %s seconds" % delay
time.sleep(delay)
print "Main: done sleeping, stopping thread"
thd.stop()
print "Main: end of program"

test()

 

[phansen]

It seems like the main thread never exits from join(), in spite of
the timeout and the likeliness of the sub thread ending.

Any idea of what I've done wrong?

Nothing at all. It works fine here. (And nice clean code
you have, by the way.)

Are you running this from the command line, or inside some
other tool, or something else unusual? What versions of
Python and OS are you using?

I'm on Win XP Pro SP 2 with Python 2.3.4.

-Peter

 

[Olivier Parisy]

Nothing at all. It works fine here. (And nice clean code
you have, by the way.)

Hey, thanks! High-level languages are nice in that you can spend more
time on polish, indeed

Are you running this from the command line, or inside some
other tool, or something else unusual? What versions of
Python and OS are you using?

Gosh, you are right: this definitely works fine in the command line.
I was running this from a Linux file manager (using "launch in a
terminal" and "keep the terminal open" options), but something
seems to be wrong with this approach.

Regards,
Olivier.