From: sam.saffron@gmail.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:96606] [Ruby master Feature#16291] Introduce support for resize in rb_ary_freeze and prefer internal use of rb_ary_freeze and rb_str_freeze for String and Array types
Date: Tue, 31 Dec 2019 06:43:38 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-83574.20191231064337.e9f2b5490b4d5236@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-16291.20191104134503@ruby-lang.org
Issue #16291 has been updated by sam.saffron (Sam Saffron).
related, see this for for the string api
https://bugs.ruby-lang.org/issues/16029#change-82018
----------------------------------------
Feature #16291: Introduce support for resize in rb_ary_freeze and prefer internal use of rb_ary_freeze and rb_str_freeze for String and Array types
https://bugs.ruby-lang.org/issues/16291#change-83574
* Author: methodmissing (Lourens Naudé)
* Status: Open
* Priority: Normal
* Assignee: nobu (Nobuyoshi Nakada)
* Target version: 2.8
----------------------------------------
References Github PR https://github.com/ruby/ruby/pull/2640
### Why?
While working on https://github.com/ruby/ruby/pull/2037#issuecomment-548633141 I also looked at the `rb_ary_freeze` helper to determine if the same optimization of shrinking capacity can be applied there as well.
Further investigation revealed that `rb_str_freeze` attempts to resize / shrink strings on freeze, but we currently don't do the same for arrays despite API for it being exposed.
The gist of the change:
* Let `rb_ary_freeze` also attempt to right size an array before freezing it
* Replaced internal use of `rb_obj_freeze` and `OBJ_FREEZE` of callsites that pass a String or Array type in with `rb_ary_freeze` and `rb_str_freeze` specifically.
### Results
Saves about 3MB of Array and String specific heap footprints on a redmine production env boot on Rails 6 (custom local upgrade - it does not officially support it yet):
```
Loading production environment (Rails 6.1.0.alpha)
irb(main):001:0> RUBY_DESCRIPTION
=> "ruby 2.7.0dev (2019-11-02T06:32:49Z master 772b0613c5) [x86_64-linux]"
irb(main):002:0> require 'objspace'
=> true
irb(main):003:0> GC.start
=> nil
irb(main):004:0> ObjectSpace.each_object(Array).sum {|o| ObjectSpace.memsize_of(o) }
=> 4451200
irb(main):005:0> ObjectSpace.each_object(String).sum {|o| ObjectSpace.memsize_of(o) }
=> 8608472
irb(main):006:0> exit
```
```
Loading production environment (Rails 6.1.0.alpha)
irb(main):001:0> RUBY_DESCRIPTION
=> "ruby 2.7.0dev (2019-11-02T16:52:34Z obj-freeze-specifi.. 3bc4048899) [x86_64-linux]"
irb(main):002:0> require 'objspace'
=> true
irb(main):003:0> GC.start
=> nil
irb(main):004:0> ObjectSpace.each_object(Array).sum {|o| ObjectSpace.memsize_of(o) }
=> 3233432
irb(main):005:0> ObjectSpace.each_object(String).sum {|o| ObjectSpace.memsize_of(o) }
=> 6748422
```
irb - the best calculator ...
```
irb(main):002:0> (4451200 - 3233432) / 1024
=> 1189
irb(main):003:0> (8608472 - 6748422) / 1024
=> 1816
```
### Open questions
* Would it make sense to let `rb_obj_freeze` switch on object type instead and apply this optimization without "polluting" internals with custom callsite changes? Native extensions can then benefit from the resize feature too.
* HOWEVER: Discovered in testing that `rb_str_freeze` can fail asserts in `rb_str_tmp_frozen_release` when sprinkled too generously especially in `io.c`. And other issues may lurk too, thus incorporating the resizing in `rb_obj_freeze` won't work. See https://github.com/ruby/ruby/pull/2640#issuecomment-549119359
I think it could also make sense to split the PR in 2:
* One changeset for `rb_ary_freeze` attempting to resize Arrays on freeze, special case internal `rb_obj_freeze` of Arrays to prefer the new API
* Apply `rb_str_resize` at internal call sites where `rb_obj_freeze` is used with String types
Thoughts?
--
https://bugs.ruby-lang.org/
Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>
prev parent reply other threads:[~2019-12-31 6:43 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-16291.20191104134503@ruby-lang.org>
2019-11-04 13:45 ` [ruby-core:95665] [Ruby master Misc#16291] Introduce support for resize in rb_ary_freeze and prefer internal use of rb_ary_freeze and rb_str_freeze for String and Array types lourens
2019-11-05 1:49 ` [ruby-core:95684] " shyouhei
2019-11-08 22:31 ` [ruby-core:95765] " lourens
2019-12-26 2:24 ` [ruby-core:96479] [Ruby master Feature#16291] " mame
2019-12-31 6:43 ` sam.saffron [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-list from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.ruby-lang.org/en/community/mailing-lists/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=redmine.journal-83574.20191231064337.e9f2b5490b4d5236@ruby-lang.org \
--to=ruby-core@ruby-lang.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).