Re: [Python-Dev] Hash to longs, and Decimal
Seems a fine idea. I don't have the time for a code review but I'll leave that up to you all. --Guido On 9/17/07, Facundo Batista [EMAIL PROTECTED] wrote: Hi everybody! In the Tracker Issue... http://bugs.python.org/issue1772851 ... Mark Dickinson came with a patch that alters in a very corner case how the hash is calculated to a long integer. This allows changes in Decimal that lead to a better hashing behaviour for big, big, really big numbers. The patch applies cleanly, all the tests pass ok (Mark also provided more tests for the hash function). I won't commit this right now; I'll delay the change for a couple of days in case somebody wants to take a look at it. Thanks! -- .Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/ ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/guido%40python.org -- --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] Hash to longs, and Decimal
On 9/17/07, Facundo Batista [EMAIL PROTECTED] wrote:
In the Tracker Issue...
http://bugs.python.org/issue1772851
... Mark Dickinson came with a patch that alters in a very corner case
how the hash is calculated to a long integer.
Much as I'd like this patch to be applied, I feel compelled to point out
that it does have a significant(?) downside: it slows down hashing of large
integers to some degree.
On my machine (Dual Xeon 2.8Ghz/SuSE Linux 10.2/gcc 4.1 with -O3), using
timeit.timeit('hash(n)') to get timings, the new hash function takes 70%
more time for 1000 digit integers, 20% longer for 100 digit integers, but
has no measurable performance impact for small (int-sized) longs. I don't
know how significant this performance hit is in the larger scheme of things.
Mark
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