I have spotted the biggest bottleneck in "bdiff.c". Actually it was
pretty easy to find after I recompiled the python interpreter and
mercurial for profiling.
In "bdiff.c" function "equatelines" allocates the minimum hash table
size, which can lead to tons of collisions. I introduced an
"overcommit" factor of 16, this is, I allocate 16 times more memory
than the minimum value. Overcommiting 128 times does not improve the
performance over the 16-times case.
# strutil.py - string utilities for Mercurial
#
# Copyright 2006 Vadim Gelfer <vadim.gelfer@gmail.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
def findall(haystack, needle, start=0, end=None):
if end is None:
end = len(haystack)
if end < 0:
end += len(haystack)
if start < 0:
start += len(haystack)
while start < end:
c = haystack.find(needle, start, end)
if c == -1:
break
yield c
start = c + 1
def rfindall(haystack, needle, start=0, end=None):
if end is None:
end = len(haystack)
if end < 0:
end += len(haystack)
if start < 0:
start += len(haystack)
while end >= 0:
c = haystack.rfind(needle, start, end)
if c == -1:
break
yield c
end = c - 1