Fix a number of problems with the need for speed code:
One is doing this sort of thing:
Py_DECREF(self->field);
self->field = newval;
Py_INCREF(self->field);
without being very sure that self->field doesn't start with a
value that has a __del__, because that almost certainly can lead
to segfaults.
As self->args is constrained to be an exact tuple we may as well
exploit this fact consistently. This leads to quite a lot of
simplification (and, hey, probably better performance).
Add some error checking in places lacking it.
Fix some rather strange indentation in the Unicode code.
Delete some trailing whitespace.
More to come, I haven't fixed all the reference leaks yet...
(If compiled without FAST search support, changed the pre-memcmp test
to check the last character as well as the first. This gave a 25%
speedup for my test case.)
Rewrote the split algorithms so they stop when maxsplit gets to 0.
Previously they did a string match first then checked if the maxsplit
was reached. The new way prevents a needless string search.
results list.
Originally it allocated 0 items and used the list growth during append. Now
it preallocates 12 items so the first few appends don't need list reallocs.
("Here are some words ."*2).split(None, 1) is 7% faster
("Here are some words ."*2).split() is is 15% faster
(Your milage may vary, see dealership for details.)
File parsing like this
for line in f:
count += len(line.split())
is also about 15% faster. There is a slowdown of about 3% for large
strings because of the additional overhead of checking if the append is
to a preallocated region of the list or not. This will be the rare case.
It could be improved with special case code but we decided it was not
useful enough.
There is a cost of 12*sizeof(PyObject *) bytes per list. For the normal
case of file parsing this is not a problem because of the lists have
a short lifetime. We have not come up with cases where this is a problem
in real life.
I chose 12 because human text averages about 11 words per line in books,
one of my data sets averages 6.2 words with a final peak at 11 words per
line, and I work with a tab delimited data set with 8 tabs per line (or
9 words per line). 12 encompasses all of these.
Also changed the last rstrip code to append then reverse, rather than
doing insert(0). The strip() and rstrip() times are now comparable.
this is on par with a corresponding find, and nearly twice as fast
as split(sep, 1)
full tests, a unicode version, and documentation will follow to-
morrow.
The SIGCHECK macro defined here has always been bizarre, but
it apparently causes compiler warnings on "Sun Studio 11".
I believe the warnings are bogus, but it doesn't hurt to make
the macro definition saner.
Bugfix candidate (but I'm not going to bother).
Michael W. Hudson
Fredrik Lundh
Richard Jones
Georg Brandl
Andrew Dalke
Martin v. Löwis
Neal Norwitz
Andrew M. Kuchling
Tim Peters
Bob Ippolito
Jack Diederich