[issue2115] __slots__ make attribute setting 10x slower
Amaury Forgeot d'Arc added the comment: __instancecheck__ is not only slower, it can also cause crashes: import abc class MyABC: __metaclass__ = abc.ABCMeta __slots__ = [a] class Unrelated: pass MyABC.register(Unrelated) u=Unrelated() assert isinstance(u, MyABC) MyABC.a.__set__(u, 3) # Boom The patch I proposed above correctly raises the error: TypeError: descriptor 'a' for 'MyABC' objects doesn't apply to 'Unrelated' object __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Amaury Forgeot d'Arc added the comment: I think I fixed the issue. svn annotate showed that the exact same optimization was applied on __slots__ read access, five years ago: r28297. -- resolution: - fixed status: open - closed __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
New submission from Jeffrey Yasskin: (On a MacBook Pro 2.33 GHz) $ ./python.exe -m timeit -s 'class Foo(object): pass' -s 'f = Foo()' 'f.num = 3' 1000 loops, best of 3: 0.13 usec per loop $ ./python.exe -m timeit -s 'class Foo(object): __slots__ = [num]' -s 'f = Foo()' 'f.num = 3' 100 loops, best of 3: 1.24 usec per loop Attribute reading isn't affected: $ ./python.exe -m timeit -s 'class Foo(object): pass' -s 'f = Foo(); f.num = 3' 'g = f.num' 1000 loops, best of 3: 0.107 usec per loop $ ./python.exe -m timeit -s 'class Foo(object): __slots__ = [num]' -s 'f = Foo(); f.num = 3' 'g = f.num' 1000 loops, best of 3: 0.101 usec per loop -- components: Interpreter Core messages: 62408 nosy: jyasskin severity: normal status: open title: __slots__ make attribute setting 10x slower type: resource usage versions: Python 2.6 __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Changes by Facundo Batista: -- nosy: +facundobatista __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Amaury Forgeot d'Arc added the comment: This slowdown is due to the new implementation of isinstance in python2.6. If I comment most of the code of PyObject_IsInstance in Objects/abstract.c (remove all __instancecheck__ stuff; leave only the last line), timings are much better, and more similar to 2.5 performance. -- nosy: +amaury.forgeotdarc __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Thomas Heller added the comment: I think this is a serious problem (and thanks, amaury, for finding the spot). comtypes, like ctypes, uses quite a bit of isinstance calls. It is the reason that the comtypes unit tests run between 8% and 25% slower with trunk than with python 2.5.1. If I comment out the code that you mentioned, python trunk is slightly faster than 2.5.1. I suggest to raise the severity. -- nosy: +theller __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Christian Heimes added the comment: I agree, Thomas -- nosy: +tiran priority: - high __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Thomas Heller added the comment: PyObject_IsSubclass() has the same problem. BTW; calling PyObject_GetAttr() with interned strings for __instancecheck__ and __subclasscheck__ brings not enough speedup. __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Amaury Forgeot d'Arc added the comment: Something interesting: - attribute setting uses PyObject_IsInstance, which is slower since the introduction of ABCs. - attribute reading uses PyObject_TypeCheck, which only searches the __mro__. Does this means that many calls to IsInstance could be replaced by TypeCheck? Of course this makes sense only for new-style classes, but it is the case for all built-in objects. __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue2115] __slots__ make attribute setting 10x slower
Amaury Forgeot d'Arc added the comment:
With this trivial patch, all tests still pass:
Index: Objects/descrobject.c
===
--- Objects/descrobject.c (revision 60754)
+++ Objects/descrobject.c (working copy)
@@ -166,7 +166,7 @@
int *pres)
{
assert(obj != NULL);
- if (!PyObject_IsInstance(obj, (PyObject *)(descr-d_type))) {
+ if (!PyObject_TypeCheck(obj, descr-d_type)) {
PyErr_Format(PyExc_TypeError,
descriptor '%.200s' for '%.100s' objects
doesn't apply to '%.100s' object,
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[issue2115] __slots__ make attribute setting 10x slower
Christian Heimes added the comment: Thomas Heller wrote: BTW; calling PyObject_GetAttr() with interned strings for __instancecheck__ and __subclasscheck__ brings not enough speedup. I've implemented the interning as static PyObject* in r60822. It should give a small speedup. __ Tracker [EMAIL PROTECTED] http://bugs.python.org/issue2115 __ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
