Op 20/03/20 om 02:10 schreef Cameron Simpson:
On 20Mar2020 00:37, duncan smith <duncan@invalid.invalid> wrote:
Thread
safety is unimportant (for my purposes), but the docs at
https://docs.python.org/2/library/collections.html#collections.deque
state "Deques support thread-safe, memory efficient appends and pops
from either side of the deque with approximately the same O(1)
performance in either direction". Looking at the output from the
profiler for my implementation with the queue it looks like a deque is
being used but there's various other stuff happening relating to thread
safety. Is the lesson from this that if all you're doing is appending
and popping, then use a deque (rather than a queue) even if you want
thread safety? (It makes quite a difference in performance for my use
case.) Cheers.
A deque will change the ordering of the elements you process. Your
list loop behaves in FIFO order, as does the queue. A dequeue (you
you're doing a heappush and a heappop) will issue you the lowest
current element on each iteration. If you merely need to process all
the elements you're good. If the order matters you need to consider that.
A deque, being thread safe, will be using a lock. There will be a
(quite small) overhead for that.
This doesn't seem correct. A deque is used to simulate a stack or a
queue. It doesn't use heappush or heappop.
Antoon.
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