Klaas wrote:
> In fact, you can make it about 4x faster by balancing:
>
> [EMAIL PROTECTED] ~]$ python -m timeit -s "from array import array"
> "array('c','\0'*200)*500"
> 10000 loops, best of 3: 32.4 usec per loop
This is an unclean minimally-tested patch which achieves reasonable
performance (about 10x faster than unpatched python):
$ ./python -m timeit -s "from array import array" "array('c',
'\0')*100000"
10000 loops, best of 3: 71.6 usec per loop
You have my permission to use this code if you want to submit a patch
to sourceforge (it needs, proper benchmarking, testing, and tidying).
-Mike
Index: Modules/arraymodule.c
===================================================================
--- Modules/arraymodule.c (revision 52849)
+++ Modules/arraymodule.c (working copy)
@@ -680,10 +680,29 @@
return NULL;
p = np->ob_item;
nbytes = a->ob_size * a->ob_descr->itemsize;
- for (i = 0; i < n; i++) {
- memcpy(p, a->ob_item, nbytes);
- p += nbytes;
- }
+
+ if (n) {
+ Py_ssize_t chunk_size = nbytes;
+ Py_ssize_t copied = 0;
+ char *src = np->ob_item;
+
+ /* copy first element */
+ memcpy(p, a->ob_item, nbytes);
+ copied += nbytes;
+
+ /* copy exponentially-increasing chunks */
+ while(chunk_size < (size - copied)) {
+ memcpy(p + copied, src, chunk_size);
+ copied += chunk_size;
+ if(chunk_size < size/10)
+ chunk_size *= 2;
+ }
+ /* copy remainder */
+ while (copied < size) {
+ memcpy(p + copied, src, nbytes);
+ copied += nbytes;
+ }
+ }
return (PyObject *) np;
}
--
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