On 23Nov2012 11:53, Ian Kelly <ian.g.ke...@gmail.com> wrote: | On Fri, Nov 23, 2012 at 9:57 AM, Peng Yu <pengyu...@gmail.com> wrote: | > The empty() returns True even after put() has been called. Why it is | > empty when there some items in it? Could anybody help me understand | > it? Thanks! | > | > ~/linux/test/python/man/library/multiprocessing/Queue/empty$ cat | > main.py | > #!/usr/bin/env python | > | > import multiprocessing | > | > queue = multiprocessing.Queue() | > print queue.empty() | > queue.put(['a', 'b']) | > queue.put(['c', 'd']) | > print queue.empty() | | According to the docs, the Queue uses a background thread to load data into it: | | When a process first puts an item on the queue a feeder thread is | started which transfers objects from a buffer into the pipe. | | Most likely it still appears to be empty because this thread has not | had a chance to run yet. If you try inserting a time.sleep() call, | you should see the queue become non-empty once the background thread | has run.
Conversely, might it not appear empty because the objects have been thrown at the pipe already, appearing to have been consumed? Or is there end-to-end handshaking controlling what .empty() tests? (Though again, the far end may have grabbed them already too.) -- Cameron Simpson <c...@zip.com.au> The ZZR-1100 is not the bike for me, but the day they invent "nerf" roads and ban radars I'll be the first in line......AMCN -- http://mail.python.org/mailman/listinfo/python-list