diff options
| -rw-r--r-- | Doc/whatsnew/whatsnew24.tex | 4 | ||||
| -rw-r--r-- | Misc/NEWS | 4 | ||||
| -rw-r--r-- | Objects/listobject.c | 11 |
3 files changed, 7 insertions, 12 deletions
diff --git a/Doc/whatsnew/whatsnew24.tex b/Doc/whatsnew/whatsnew24.tex index 1fbc298..4720eea 100644 --- a/Doc/whatsnew/whatsnew24.tex +++ b/Doc/whatsnew/whatsnew24.tex @@ -260,8 +260,8 @@ yellow 5 \begin{itemize} \item The machinery for growing and shrinking lists was optimized - for speed and for space efficiency. Small lists (under six elements) - never over-allocate by more than one element. Large lists do not + for speed and for space efficiency. Small lists (under eight elements) + never over-allocate by more than three elements. Large lists do not over-allocate by more than 1/8th. Appending and popping from lists now runs faster due to more efficient code paths and less frequent use of the underlying system realloc(). List comprehensions also @@ -19,8 +19,8 @@ Core and builtins - Changed the internal list over-allocation scheme. For larger lists, overallocation ranged between 3% and 25%. Now, it is a constant 12%. - For smaller lists (n<=5), overallocation was upto eight bytes. Now, - the overallocation is no more than one byte -- this improves space + For smaller lists (n<8), overallocation was upto eight elements. Now, + the overallocation is no more than three elements -- this improves space utilization for applications that have large numbers of small lists. - Support for arbitrary objects supporting the read-only buffer diff --git a/Objects/listobject.c b/Objects/listobject.c index 3a84229..a34810e 100644 --- a/Objects/listobject.c +++ b/Objects/listobject.c @@ -30,13 +30,10 @@ list_resize(PyListObject *self, int newsize) * for additional growth. The over-allocation is mild, but is * enough to give linear-time amortized behavior over a long * sequence of appends() in the presence of a poorly-performing - * system realloc() (which is a reality, e.g., across all flavors - * of Windows, with Win9x behavior being particularly bad -- and - * we've still got address space fragmentation problems on Win9x - * even with this scheme, although it requires much longer lists to - * provoke them than it used to). + * system realloc(). + * The growth pattern is: 0, 4, 8, 16, 25, 35, 46, 58, 72, 88, ... */ - _new_size = (newsize >> 3) + (self->ob_size < 3 ? 1 : 6) + newsize; + _new_size = (newsize >> 3) + (self->ob_size < 8 ? 3 : 6) + newsize; items = self->ob_item; if (_new_size <= ((~(size_t)0) / sizeof(PyObject *))) PyMem_RESIZE(items, PyObject *, _new_size); @@ -316,8 +313,6 @@ list_length(PyListObject *a) return a->ob_size; } - - static int list_contains(PyListObject *a, PyObject *el) { |