Alexandru Mosoi wrote:
how is Queue intended to be used? I found the following code in python
manual, but I don't understand how to stop consumers after all items
have been produced. I tried different approaches but all of them
seemed incorrect (race, deadlock or duplicating queue functionality)
def worker():
while True:
item = q.get()
do_work(item)
q.task_done()
q = Queue()
for i in range(num_worker_threads):
t = Thread(target=worker)
t.setDaemon(True)
t.start()
for item in source():
q.put(item)
q.join() # block until all tasks are done
ok. I think I figured it out :). let me know what you think
global num_tasks, num_done, queue
num_tasks = 0
num_done = 0
queue = Queue()
# producer
num_tasks += 1
for i in items:
num_tasks += 1
queue.put(i)
what's the point of using a thread-safe queue if you're going to use a
non-thread-safe counter? if you want to write broken code, you can do
that in a lot fewer lines ;-)
as others have mentioned, you can use sentinels:
http://effbot.org/librarybook/queue.htm
or, in Python 2.5 and later, the task_done/join pattern shown here:
http://docs.python.org/lib/QueueObjects.html
</F>
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