Message 188626 - Python tracker

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Author	vstinner
Recipients	kushal.das, nedbat, neologix, pitrou, trent, vstinner
Date	2013-05-07.07:17:17
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1367911037.56.0.199898332543.issue17914@psf.upfronthosting.co.za>
In-reply-to

Content
> I don't see exactly what this C implementation brings over the one > in multiprocessing (which is written in Python)? multiprocessing.cpu_count() creates a subprocess on BSD and Darwin to get the number of CPU. Calling sysctl() or sysctlnametomib() should be faster and use less memory. On Windows, GetSystemInfo() is called instead of reading an environment variable. I suppose that this function is more reliable. Trent's os.cpu_count() returns -1 if the count cannot be read, multiprocessing.cpu_count() raises NotImplementedError.

> I don't see exactly what this C implementation brings over the one
> in multiprocessing (which is written in Python)?

multiprocessing.cpu_count() creates a subprocess on BSD and Darwin to get the number of CPU. Calling sysctl() or sysctlnametomib() should be faster and use less memory.

On Windows, GetSystemInfo() is called instead of reading an environment variable. I suppose that this function is more reliable.

Trent's os.cpu_count() returns -1 if the count cannot be read, multiprocessing.cpu_count() raises NotImplementedError.

History
Date	User	Action	Args
2013-05-07 07:17:17	vstinner	set	recipients: + vstinner, pitrou, nedbat, trent, neologix, kushal.das
2013-05-07 07:17:17	vstinner	set	messageid: <1367911037.56.0.199898332543.issue17914@psf.upfronthosting.co.za>
2013-05-07 07:17:17	vstinner	link	issue17914 messages
2013-05-07 07:17:17	vstinner	create