Message 385820 - Python tracker

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Author	abo
Recipients	abo, mark.dickinson, rhettinger
Date	2021-01-27.23:24:41
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<[email protected]>
In-reply-to

Content
I had a look at the C implementation of getrandbits() and spotted this; https://github.com/python/cpython/blob/64fc105b2d2faaeadd1026d2417b83915af6622f/Modules/_randommodule.c#L487 In my case I was also being hit by randrange(2**32) calling getrandbits(33) just pushing it past using the optimized fast-path for ranges needing <=32 bits. So not only was it calling getrandbits() 2x as many times as necessary, under the hood it was generating 64 random bits each time using a slow path.

I had a look at the C implementation of getrandbits() and spotted this;

https://github.com/python/cpython/blob/64fc105b2d2faaeadd1026d2417b83915af6622f/Modules/_randommodule.c#L487

In my case I was also being hit by randrange(2**32) calling getrandbits(33) just pushing it past using the optimized fast-path for ranges needing <=32 bits. So not only was it calling getrandbits() 2x as many times as necessary, under the hood it was generating 64 random bits each time using a slow path.

History
Date	User	Action	Args
2021-01-27 23:24:41	abo	set	recipients: + abo, rhettinger, mark.dickinson
2021-01-27 23:24:41	abo	set	messageid: <[email protected]>
2021-01-27 23:24:41	abo	link	issue43040 messages
2021-01-27 23:24:41	abo	create