python queue get size, use qsize() or len()?

Question

I've seen instances where qsize() and len() has been used to compute the size of the queue. What is the distinction between the two?

Related question: [python - Why is len() not implemented for Queues? - Stack Overflow](https://stackoverflow.com/questions/47585367/why-is-len-not-implemented-for-queues) — user202729, Aug 14 '21 at 03:16

score 19 · Accepted Answer · answered Dec 18 '13 at 00:14

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For most containers, you'll want len, but Queue.Queue doesn't actually support len. This may be because it's old or because getting the length of a queue in a multithreaded environment isn't particularly useful. In any case, if you want the (approximate) size of a Queue, you want qsize.

answered Dec 18 '13 at 00:14

user2357112

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len might tempt people to check for nonzero length before doing a get, assuming that the get won't block. – dstromberg Dec 18 '13 at 00:19
I am getting this crash on Mac while calling qsize return self._maxsize - self._sem._semlock._get_value() NotImplementedError any help ? – Venu Gopal Tewari Jun 14 '19 at 05:23
why is it approximate? What if you need exact? – Aaron Oommen Jun 21 '19 at 14:59

score 2 · Answer 2 · edited Dec 21 '20 at 17:23

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queue.qsize() doesn't return the number of bytes in the queue. It returns the number of "things" placed in the queue.

If you put 5 byte-arrays of 100 bytes in the queue, the qsize() will be 5, not 500.

edited Dec 21 '20 at 17:23

Kate Orlova

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answered Dec 15 '17 at 07:02

user3145004

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python queue get size, use qsize() or len()?

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