GNU bug report logs - #21616
[PATCH] Enable sorting of JSON object keys when encoding

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Message #11 received at 21616 <at> debbugs.gnu.org (full text, mbox):

From: Simen Heggestøyl <simenheg <at> gmail.com>
To: Dmitry Gutov <dgutov <at> yandex.ru>
Cc: 21616 <at> debbugs.gnu.org
Subject: Re: bug#21616: [PATCH] Enable sorting of JSON object keys when
 encoding
Date: Wed, 11 Nov 2015 19:59:33 +0100

[Message part 1 (text/plain, inline)]

Hello, Dmitry.

On Mon, Nov 9, 2015 at 1:01 AM, Dmitry Gutov <dgutov <at> yandex.ru> wrote:
> Call it json-[encode-]key-sort-predicate, maybe?

Indeed, "predicate" seems more appropriate. I'll change the name.

> The unification part makes me concerned, again, from the performance 
> standpoint. Did you do any measuring here?

I didn't before now, but as you feared, the performance became
measurably worse when encoding plists and hash-tables.

I performed some benchmarks on the same 560K JSON file as before
(http://folk.uio.no/simenheg/huge.json), with the following results:

With json-object-type set to hash-table:

 Before the patch:
 (benchmark-run 100 (json-encode huge))
      ⇒ (17.396825399 800 7.954568797999999)

 After the patch:
 (benchmark-run 100 (json-encode huge))
      ⇒ (19.338006244000002 700 9.664285849000013)

With json-object-type set to plist:

 Before the patch:
 (benchmark-run 100 (json-encode huge))
      ⇒ (15.152158676 1101 7.109026906)

 After the patch:
 (benchmark-run 100 (json-encode huge))
      ⇒ (18.122579887 777 8.46547749400001)

How about keeping the old encoding code as the default, and only do the
{hash-table, plist} → alist transform when the output is to be sorted?
That keeps new code to a minimum, and the they would need to be
transformed to an intermediate structure to be sorted anyway.

A patch implementing this suggestion is attached. Here are the same
benchmarks with the new patch applied:

With json-object-type set to hash-table:

 (benchmark-run 100 (json-encode huge))
      ⇒ (17.229601604 750 8.015517397999995)

With json-object-type set to plist:

 (benchmark-run 100 (json-encode huge))
      ⇒ (14.363185863 1101 6.992225689000007)

-- Simen

[Message part 2 (text/html, inline)]

[0001-Enable-sorting-of-JSON-object-keys-when-encoding.patch (text/x-patch, attachment)]

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