From: "Sébastien Chapuis" <sebastien@chapu.is>
To: Eli Zaretskii <eliz@gnu.org>
Cc: yyoncho@gmail.com, 31138@debbugs.gnu.org
Subject: bug#31138: Native json slower than json.el
Date: Sat, 23 Mar 2019 09:59:23 +0800 [thread overview]
Message-ID: <CAN2Hsvw3DF7ztuBQJ3MUuyGcmrpiVxbAvsyLUebaaV73x1r4yQ@mail.gmail.com> (raw)
In-Reply-To: <838t9o4hvl.fsf@gnu.org>
Hello,
I tried to find the cause of this but still without any success.
Here is a reproducible case:
You can download the json file at:
https://gist.githubusercontent.com/yyoncho/dec968b69185305ed02741e18b27a82d/raw/334b0a51bc52cc3c98edb8ff4bccb5fc4531842b/large.json
Open the file with `emacs -Q large.json`.
Switch to the scratch buffer and run:
```
(with-current-buffer "large.json"
(benchmark-run 10 (json-parse-string (buffer-string))))
;;; (2.5371836119999998 10 0.111044641)
(with-current-buffer "large.json"
(let ((str (buffer-string)))
(benchmark-run 10 (with-temp-buffer (json-parse-string str)))))
;;; (1.510604359 10 0.13192760000000003)
(with-current-buffer "large.json"
(let ((str (buffer-string)))
(benchmark-run 10 (with-temp-buffer (json-read-from-string str)))))
;;; (1.970248228 114 1.058150570000001)
```
Thanks,
Sebastien Chapuis
Le dim. 15 avr. 2018 à 23:19, Eli Zaretskii <eliz@gnu.org> a écrit :
>
> > From: Sebastien Chapuis <sebastien@chapu.is>
> > Cc: 31138@debbugs.gnu.org
> > Date: Sun, 15 Apr 2018 16:40:18 +0200
> >
> >
> > > I'm surprised that the slowdown due to the conversion is so large,
> > > though. It doesn't feel right, even with a 4MB string.
> >
> > I've digged a bit to know why it is so slow, and I've found that if I'm
> > wrapping `json-parse-string` with a `with-temp-buffer`, it is now way
> > faster:
> >
> > results of benchmark-run with a string of 4043212 characters
> > ```
> > (with-temp-buffer (json-parse-string str)):
> > (0.814315554 1 0.11941178500000005)
> >
> > (json-parse-string str):
> > (11.542233167 1 0.14954429599999997)
> >
> > (with-temp-buffer (json-read-from-string str)):
> > (5.9781185610000005 29 4.967349412000001)
> >
> > (json-read-from-string str):
> > (5.601267 24 4.723292248000001)
> > ```
>
> Interesting.
>
> > Any idea why ?
>
> Where did str come from? Did you insert it into the buffer or
> something? Could that explain the difference in performance?
>
> More generally, can you post the string you are using for the
> benchmarking, and the benchmark code as well? That would make the
> discussion less abstract.
>
> > > Yes, it's necessary, because the input string may include raw bytes,
> > > which will crash Emacs if not handled properly.
> >
> > The Jansson documentation guarantee that the strings returned
> > from the library are always UTF-8 encoded [1].
>
> You assume that the library has no bugs, yes? Because if it does,
> then we might crash Emacs by trusting it so much. Letting invalid
> bytes creep into Emacs buffers and strings is a sure recipe for an
> eventual crash.
>
> > By knowing that guarantee, is it possible to reconsider the use of
> > code_convert_string ?
>
> Since it's already much faster than a Lisp implementation, why would
> we want to risk crashing an Emacs session by omitting the decoding?
>
> > Encoding a string to UTF-8 which is already UTF-8 encoded seems
> > useless..
>
> It's decoding, not encoding, and the process of decoding examines
> every sequence in the byte stream and ensures they are valid UTF-8.
>
> Emacs never trusts any external data to be what the user or Lisp tell
> it is; I see no reason why we should make an exception in this
> particular case.
>
> Thanks.
next prev parent reply other threads:[~2019-03-23 1:59 UTC|newest]
Thread overview: 161+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-12 19:13 bug#31138: Native json slower than json.el Sebastien Chapuis
2018-04-13 7:24 ` Eli Zaretskii
2018-04-15 14:40 ` Sebastien Chapuis
2018-04-15 15:19 ` Eli Zaretskii
2019-03-23 1:59 ` Sébastien Chapuis [this message]
2019-03-23 8:15 ` Eli Zaretskii
2019-03-23 9:40 ` Eli Zaretskii
2019-03-23 12:59 ` Sébastien Chapuis
2019-03-23 13:21 ` Eli Zaretskii
2019-03-23 13:31 ` yyoncho
2019-03-23 14:00 ` Eli Zaretskii
2019-03-23 14:32 ` yyoncho
2019-03-23 14:55 ` Eli Zaretskii
2019-03-23 15:27 ` yyoncho
2019-03-23 16:29 ` Eli Zaretskii
[not found] ` <CACCVLQW=_YngoTwXU+1BDvVVy5jwxSmDFUQJBvs8=PrP=fn=aw@mail.gmail.com>
2019-03-23 18:50 ` Eli Zaretskii
2019-03-23 20:23 ` yyoncho
2019-03-23 20:54 ` Eli Zaretskii
2019-03-23 21:04 ` yyoncho
2019-03-24 3:32 ` Eli Zaretskii
2019-03-24 9:35 ` yyoncho
2019-03-24 11:20 ` Eli Zaretskii
2019-03-24 11:37 ` yyoncho
2019-03-24 15:15 ` Eli Zaretskii
2019-03-24 18:24 ` yyoncho
2019-03-24 18:28 ` Eli Zaretskii
2019-03-24 20:57 ` yyoncho
2019-03-25 3:32 ` Eli Zaretskii
2019-03-25 5:44 ` yyoncho
2019-03-25 16:42 ` Eli Zaretskii
2019-03-25 18:20 ` yyoncho
2019-03-25 18:25 ` Eli Zaretskii
2019-03-25 19:16 ` yyoncho
2019-03-25 20:05 ` Eli Zaretskii
2019-03-25 21:34 ` yyoncho
2019-03-25 23:04 ` Dmitry Gutov
2019-03-26 3:51 ` Eli Zaretskii
2019-03-26 16:14 ` Eli Zaretskii
2019-03-26 17:45 ` yyoncho
2019-03-26 18:11 ` Eli Zaretskii
2019-03-26 18:15 ` yyoncho
2019-04-16 1:36 ` Dmitry Gutov
2019-04-16 2:38 ` Eli Zaretskii
2019-04-16 13:50 ` Dmitry Gutov
2019-04-16 15:13 ` Eli Zaretskii
2019-04-16 15:30 ` Dmitry Gutov
2019-04-16 16:10 ` Eli Zaretskii
2019-04-16 16:23 ` Dmitry Gutov
2019-04-16 16:44 ` Eli Zaretskii
2019-04-21 8:58 ` Eli Zaretskii
2019-04-21 9:15 ` Dmitry Gutov
2019-04-21 9:31 ` Eli Zaretskii
2019-04-21 10:23 ` yyoncho
2019-04-21 10:37 ` Eli Zaretskii
2019-04-21 11:38 ` yyoncho
2019-04-21 12:15 ` Eli Zaretskii
2019-04-21 13:28 ` yyoncho
2019-04-21 19:03 ` Eli Zaretskii
2019-04-21 20:13 ` Eli Zaretskii
2019-04-22 5:38 ` yyoncho
2019-04-22 8:01 ` Eli Zaretskii
2019-04-22 13:00 ` yyoncho
2019-04-22 13:17 ` Eli Zaretskii
2019-04-22 16:53 ` Ivan
2019-04-22 16:58 ` Eli Zaretskii
2019-04-21 22:17 ` Dmitry Gutov
2019-04-22 7:16 ` Eli Zaretskii
2019-04-22 13:54 ` Dmitry Gutov
2019-04-22 15:24 ` Eli Zaretskii
2019-04-22 15:31 ` Dmitry Gutov
2019-04-21 12:59 ` Philipp Stephani
2019-04-21 13:09 ` yyoncho
2019-04-21 13:33 ` Philipp Stephani
2019-04-22 11:48 ` Dmitry Gutov
2019-04-22 12:12 ` Eli Zaretskii
2019-04-22 12:24 ` Dmitry Gutov
2019-04-22 13:02 ` Eli Zaretskii
2019-04-22 15:02 ` Dmitry Gutov
2019-04-22 15:36 ` Eli Zaretskii
2019-04-22 16:16 ` Dmitry Gutov
2019-04-22 16:28 ` Eli Zaretskii
2019-04-22 16:44 ` Dmitry Gutov
2019-04-22 16:50 ` Eli Zaretskii
2019-04-22 17:05 ` Dmitry Gutov
2019-04-22 17:24 ` Eli Zaretskii
2019-04-22 21:03 ` Dmitry Gutov
2019-04-23 10:22 ` Eli Zaretskii
2019-04-23 11:39 ` Dmitry Gutov
2019-04-23 13:19 ` Eli Zaretskii
2019-04-22 16:49 ` Eli Zaretskii
2019-04-22 17:11 ` Dmitry Gutov
2019-04-22 17:26 ` Eli Zaretskii
2019-04-22 22:23 ` Dmitry Gutov
2019-04-23 6:00 ` Eli Zaretskii
2019-04-23 9:46 ` Philipp Stephani
2019-04-23 10:38 ` Eli Zaretskii
2019-04-23 10:44 ` Dmitry Gutov
2019-04-24 2:23 ` Richard Stallman
2019-04-22 17:12 ` Eli Zaretskii
2019-04-22 21:00 ` Dmitry Gutov
2019-04-21 22:14 ` Dmitry Gutov
2019-04-22 7:06 ` Eli Zaretskii
2019-04-21 22:12 ` Dmitry Gutov
2019-04-22 7:03 ` Eli Zaretskii
2019-04-22 11:46 ` Dmitry Gutov
2019-04-22 12:07 ` Eli Zaretskii
2019-04-22 12:58 ` Dmitry Gutov
2019-04-22 13:12 ` Eli Zaretskii
2019-04-22 13:58 ` Dmitry Gutov
2019-04-22 15:25 ` Eli Zaretskii
2019-04-22 15:41 ` Dmitry Gutov
2019-04-22 15:50 ` Eli Zaretskii
2019-04-22 16:00 ` Dmitry Gutov
2019-04-22 16:22 ` Eli Zaretskii
2019-04-22 19:55 ` Dmitry Gutov
2019-04-22 20:28 ` Eli Zaretskii
2019-04-23 11:52 ` Dmitry Gutov
2019-04-23 12:15 ` Eli Zaretskii
2019-04-23 12:37 ` yyoncho
2019-04-23 13:09 ` Eli Zaretskii
2019-04-23 13:27 ` yyoncho
2019-04-23 14:24 ` Eli Zaretskii
2019-04-23 12:37 ` Sébastien Chapuis
2019-04-23 13:10 ` Eli Zaretskii
2019-04-23 14:22 ` Dmitry Gutov
2019-04-23 14:40 ` Philipp Stephani
2019-04-23 15:09 ` Eli Zaretskii
2019-04-23 15:17 ` Eli Zaretskii
2019-04-23 15:36 ` yyoncho
2019-04-23 15:39 ` Eli Zaretskii
2019-04-23 15:43 ` yyoncho
2019-04-23 22:34 ` Dmitry Gutov
2019-04-24 6:20 ` Eli Zaretskii
2019-04-24 6:57 ` Dmitry Gutov
2019-04-24 7:28 ` Eli Zaretskii
2019-04-24 9:52 ` Dmitry Gutov
2019-04-23 14:58 ` Eli Zaretskii
2019-04-24 15:55 ` Dmitry Gutov
2019-04-24 16:21 ` Eli Zaretskii
2019-04-24 16:46 ` Dmitry Gutov
2019-04-24 17:06 ` Eli Zaretskii
2019-04-24 17:36 ` Dmitry Gutov
2019-04-24 17:43 ` Eli Zaretskii
2019-04-24 20:25 ` Dmitry Gutov
2019-04-25 10:44 ` Eli Zaretskii
2019-04-25 14:27 ` Dmitry Gutov
2020-08-22 23:28 ` Lars Ingebrigtsen
2020-08-23 5:50 ` Eli Zaretskii
2019-04-23 14:50 ` Andy Moreton
2019-04-23 15:03 ` Eli Zaretskii
2019-04-23 15:44 ` Andy Moreton
2019-04-22 11:36 ` Dmitry Gutov
2019-04-22 12:01 ` Eli Zaretskii
2019-04-22 13:11 ` Dmitry Gutov
2019-03-30 9:07 ` Eli Zaretskii
2019-04-22 18:20 ` Alex Gramiak
2019-04-22 18:27 ` Eli Zaretskii
2019-04-22 19:52 ` Alex Gramiak
2019-04-22 20:05 ` Dmitry Gutov
2019-04-23 3:06 ` Alex Gramiak
2019-04-23 11:44 ` Dmitry Gutov
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