Stefan Behnel <sco...@users.sourceforge.net> added the comment:
> Any benchmark numbers for the slice cache?
I ran the list tests in pybench and got this:
Test minimum run-time average run-time
this other diff this other diff
--------------------------------------------------------------------
ListSlicing: 66ms 67ms -2.2% 67ms 68ms -2.7%
SmallLists: 61ms 64ms -4.5% 61ms 65ms -5.6%
--------------------------------------------------------------------
Totals: 127ms 131ms -3.3% 128ms 133ms -4.1%
Repeating this gave me anything between 1.5% and 3.5% in total, with >2% for
the small lists benchmark (which is the expected best case as slicing large
lists obviously dominates the slice object creation).
IMHO, even 2% would be pretty good for such a small change.
> Also, is the call to PyObject_INIT necessary?
In any case, the ref-count needs to be re-initialised to 1. A call to
_Py_NewReference() would be enough, though, following the example in
listobject.c. So you can replace
PyObject_INIT(obj, &PySlice_Type);
by
_Py_NewReference((PyObject *)obj);
in the patch. New patch attached.
----------
Added file: http://bugs.python.org/file20650/slice-object-cache.patch
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