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.
import os
from mercurial import hg, ui, commands
u = ui.ui()
repo = hg.repository(u, 'test1', create=1)
os.chdir('test1')
# create 'foo' with fixed time stamp
f = file('foo', 'w')
f.write('foo\n')
f.close()
os.utime('foo', (1000, 1000))
# add+commit 'foo'
repo.add(['foo'])
repo.commit(text='commit1', date="0 0")
print "workingfilectx.date =", repo.workingctx().filectx('foo').date()