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Speedup types.coroutine() #68513
Description
| BPO | 24325 |
|---|---|
| Nosy | @gvanrossum, @ncoghlan, @scoder, @vstinner, @larryhastings, @asvetlov, @markshannon, @vadmium, @1st1 |
| Dependencies | |
| Files |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = 'https://github.com/1st1'
closed_at = <Date 2018-01-29.20:10:43.091>
created_at = <Date 2015-05-29.16:23:27.316>
labels = ['type-feature', 'library']
title = 'Speedup types.coroutine()'
updated_at = <Date 2018-01-29.20:10:43.089>
user = 'https://github.com/1st1'bugs.python.org fields:
activity = <Date 2018-01-29.20:10:43.089>
actor = 'yselivanov'
assignee = 'yselivanov'
closed = True
closed_date = <Date 2018-01-29.20:10:43.091>
closer = 'yselivanov'
components = ['Library (Lib)']
creation = <Date 2015-05-29.16:23:27.316>
creator = 'yselivanov'
dependencies = ['24400']
files = ['39547', '39563', '39754', '39774', '39803']
hgrepos = []
issue_num = 24325
keywords = ['patch']
message_count = 20.0
messages = ['244388', '244418', '244447', '244451', '244490', '244504', '245575', '245581', '245655', '245756', '245761', '245764', '246117', '246118', '246123', '246139', '246142', '246148', '246330', '311162']
nosy_count = 11.0
nosy_names = ['gvanrossum', 'ncoghlan', 'scoder', 'vstinner', 'larry', 'Arfrever', 'asvetlov', 'Mark.Shannon', 'python-dev', 'martin.panter', 'yselivanov']
pr_nums = []
priority = 'normal'
resolution = 'rejected'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue24325'
versions = ['Python 3.5', 'Python 3.6']
Activity
1st1 commentedon May 29, 2015
Attached patch provides an implementation (part of it) of types.coroutine in C.
The problem with the current pure Python implementation is that it copies the code object of the generator function, which is a small overhead during import.
I'm not sure if this should be merged in 3.5 at all. Please take a look at the patch.
1st1 commentedon May 29, 2015
Attached is the second iteration of the patch. Now, besides just speeding up types.coroutine() for pure python generator functions, it also provides a better wrapper around generator-like objects.
larryhastings commentedon May 30, 2015
This looks big and complicated. I'd prefer this skipped 3.5 and just went into 3.6.
scoder commentedon May 30, 2015
I would still like to see a patch in Py3.5 that only flips the bit in C when "_types" is available and otherwise falls back to the existing Python code that creates a new code object. This part is much cleaner and faster to do in C than in the current Python implementation.
1st1 commentedon May 30, 2015
Larry, can you accept the first version of the patch (only function that patches code object's co_flags) after beta2?
I'm OK if you think it should only be committed in 3.6, but I also agree with Stefan, that using C is better in this particular case.
gvanrossum commentedon May 31, 2015
Since it's a speedup it could also go into 3.5.1.
On May 30, 2015 1:22 PM, "Yury Selivanov" <[email protected]> wrote:
1st1 commentedon Jun 20, 2015
Larry, Nick,
Looking at how bpo-24400 progresses, I think it would be really great if we can merge this one in 3.5.0. It also makes it unnecessary to merge bpo-24468 in 3.5.
ncoghlan commentedon Jun 21, 2015
+1 from me for merging this for 3.5.0 and deferring bpo-24468 (which now proposes making _opcode a builtin module to allow compiler constants to be easily shared between C code and Python code) to 3.6 instead.
The design changes to address bpo-24400 cleaned up various aspect of both the internal architecture and the public data model of PEP-492, and the latest draft of this patch benefits accordingly.
1st1 commentedon Jun 22, 2015
A rebased version of the patch is attached (now a "review" link should appear).
Nick, Stefan, please take a look.
Larry, can we merge this in 3.5.0? I've invested a lot of time to have 100% test coverage; the test suite is very elaborate now. There seems to be no refleaks too. I think this change is a very natural continuation of what we've done in bpo-24400.
python-dev commentedon Jun 24, 2015
New changeset eb6fb8e2f995 by Yury Selivanov in branch '3.5':
Issue bpo-24325, bpo-24400: Add more unittests for types.coroutine; tweak wrapper implementation.
https://hg.python.org/cpython/rev/eb6fb8e2f995
New changeset 7a2a79362bbe by Yury Selivanov in branch 'default':
Merge 3.5 (Issue bpo-24325, bpo-24400)
https://hg.python.org/cpython/rev/7a2a79362bbe
python-dev commentedon Jun 24, 2015
New changeset 9aee273bf8b7 by Yury Selivanov in branch '3.5':
Issue bpo-24400, bpo-24325: More tests for types._GeneratorWrapper
https://hg.python.org/cpython/rev/9aee273bf8b7
New changeset fa097a336079 by Yury Selivanov in branch 'default':
Merge 3.5 (issue bpo-24325 & bpo-24400)
https://hg.python.org/cpython/rev/fa097a336079
1st1 commentedon Jun 24, 2015
I've committed new unittests from this patch (as they are applicable to pure Python implementation of the wrapper too)
The patch now contains only the C implementation of the wrapper and should be ready to be committed. Larry?
larryhastings commentedon Jul 3, 2015
Help me to understand here. You want to check in a patch adding 300 new lines of C code to the types module during beta, for a speed optimization, after we've already hit beta?
While I like speedups as much as the next guy, I would be happier if this waited for 3.6.
Of course, if Guido is overruling me, then Guido is overruling me and you get to check it in.
larryhastings commentedon Jul 3, 2015
Oh, wait, I was confusing myself. This is that new module you guys created for type hints, and this is a new object with no installed base. (Right?)
Yeah, you can check it in for 3.5.
1st1 commentedon Jul 3, 2015
No, you were right in your previous comment...
This speedup will mostly affect code compiled with Cython. See the following example:
@asyncio.coroutine
def coro():
yield from ...
Cython will compile "coro" into a function, that returns a generator-like object. "asyncio.coroutine" will wrap this function, and, therefore, the optimized by Cython generator-like object will be wrapped too (to provide an __await__ method).
This patch provides a faster wrapper for such generator-like objects. Since the whole point of using Cython is to squeeze as much performance as possible, I think it's essential to have this optimization in 3.5 (or at least in 3.5.1 as Guido suggested).
It's a lot of C code, I agree. I only can say that I did my best to write very extensive unittests, and so I hope that it won't cause any trouble.
scoder commentedon Jul 3, 2015
This is not purely about speeding up the code. It's also about avoiding to replace the code object of a function, which is essentially a big and clumsy hack only to achieve setting a flag. Some tools, namely line_profiler, use the current code object as a dict key for state keeping. Replacing the reference in "__code__" might confuse them if they happened to catch a reference before.
That's why I asked for applying at least the simple patch that sets the flag with a C level helper function. But I'd be ok with applying the latest patch as it is. The non-flag-setting parts are simple and a straight forward translation of the current Python code.
markshannon commentedon Jul 3, 2015
Does this have a measurable performance impact?
I'd be surprised if it did.
W.r.t. to profiling, the undecorated form will never be visible to any code other than the decorator, so won't show up in the profiler.
scoder commentedon Jul 3, 2015
Assuming that 1) it's the first and/or only decorator, 2) it's used to
decorate a generator function that returns its own generator and 3) it's
really used as a decorator and not as a general helper function to safely
wrap some object that was created somewhere else.
markshannon commentedon Jul 5, 2015
If type.coroutine is not the first and only decorator, then things may be even worse.
Code objects are currently immutable.
This change would mean that a call to types.coroutine in one place in the code would change the semantics of another piece of code in a potentially surprising way.
I think creating a copy is probably the best thing to.
1st1 commentedon Jan 29, 2018
Closing this one now--there's no point in speeding up types.coroutine anymore.