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Subject: [ruby-core:72530] [Ruby trunk - Feature #11339] [PATCH] io.c: avoid kwarg parsing in C API
Date: Mon, 28 Dec 2015 00:13:54 +0000
Message-ID: <> (raw)
In-Reply-To: <>

Issue #11339 has been updated by Charles Nutter.

Eric Wong wrote:
>  Using globals or TLS would introduce subtle reentrancy problems
>  when calls are nested.  I don't want to create more C-APIs
>  we need to support long-term, either.

The global would only be used between the runtime making a call with keyword arguments and the consumption of those arguments for variable initialization in a C method. There's no nesting of calls, and once the C method has consumed the values in the global (i.e. immediately before doing anything else), it is not touched until the next call with keywords from Ruby to C.

>  JRuby doesn't use our current prelude.rb, I hope.

We use parts of it, to stay in alignment with the load order of things like RubyGems and did_you_mean. We won't use the IO parts.

The socket changes are in socket.rb, which is part of stdlib and we *do* use it. I'll have to maintain another patch to remove this stuff.

>  Fwiw, I like the Rubinius philosophy of using Ruby as much as
>  possible a lot and tried to contribute there back in the day.

Yes, except that this doesn't buy anything because 99% of the logic of these methods still lives within C code. If you were also moving the body of these nonblock methods into Ruby, I'd see some value. You've removed a couple lines of C and added a couple lines of Ruby. And now there's going to be an extra method in stack traces and an extra Ruby frame allocated for every call.

Feature #11339: [PATCH] io.c: avoid kwarg parsing in C API

* Author: Eric Wong
* Status: Closed
* Priority: Normal
* Assignee: 
rb_scan_args and hash lookups for kwargs in the C API are clumsy and
slow.  Instead of improving the C API for performance, use Ruby
instead :)

Implement IO#read_nonblock and IO#write_nonblock in prelude.rb
to avoid argument parsing via rb_scan_args and hash lookups.

This speeds up IO#write_nonblock and IO#read_nonblock benchmarks
in both cases, including the original non-idiomatic case where
the `exception: false' hash is pre-allocated to avoid GC pressure.

Now, writing the kwargs in natural, idiomatic Ruby is fastest.
I've added the noex2 benchmark to show this.

target 0: a (ruby 2.3.0dev (2015-07-08 trunk 51190) [x86_64-linux]) at "a/ruby"
target 1: b (ruby 2.3.0dev (2015-07-08 nonblock-kwarg 51190) [x86_64-linux]) at "b/ruby"
raw data:

  [[2.5436805468052626, 2.5724728293716908, 2.4915440678596497],
   [2.478000810369849, 2.4285155069082975, 2.462410459294915]]],
  [[3.012514788657427, 3.034533655270934, 2.9972082190215588],
   [2.135501991957426, 2.146781364455819, 2.0429874528199434]]]]

Elapsed time: 30.348340944 (sec)
benchmark results:
minimum results in each 3 measurements.
Execution time (sec)
name    a       b
io_nonblock_noex        2.492   2.429
io_nonblock_noex2       2.997   2.043

Speedup ratio: compare with the result of `a' (greater is better)
name    b
io_nonblock_noex        1.026
io_nonblock_noex2       1.467

Note: I plan to followup commits for other *_nonblock methods
Eventually, I even wish to deprecate rb_scan_args :D

For what it's worth, I'm more excited about this change than usual
and hope to use prelude.rb more.

0001-io.c-avoid-kwarg-parsing-in-C-API.patch (6.88 KB)


  parent reply	other threads:[~2015-12-27 23:41 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2015-07-07 21:59 ` [ruby-core:69892] [Ruby trunk - Feature #11339] [Open] " normalperson
2015-07-15 19:41   ` [ruby-core:69983] " Eric Wong
2015-07-16  3:46     ` [ruby-core:69990] " SASADA Koichi
2015-07-16  7:01       ` [ruby-core:69995] " Eric Wong
2015-07-16  9:17         ` [ruby-core:69999] " SASADA Koichi
2015-10-09 23:35           ` [ruby-core:71035] " Eric Wong
2015-11-10 22:27   ` [ruby-core:71435] " Eric Wong
2015-12-02  2:23   ` [ruby-core:71789] " Eric Wong
2015-11-11  5:20 ` [ruby-core:71439] [Ruby trunk - Feature #11339] " matz
2015-11-12  2:03   ` [ruby-core:71459] " Eric Wong
2015-11-12  9:53     ` [ruby-core:71462] " Eric Wong
2015-11-18  2:07     ` [ruby-core:71539] " Eric Wong
2015-11-13  4:18   ` [ruby-core:71473] " Eric Wong
2015-11-13  5:46     ` [ruby-core:71478] " SASADA Koichi
2015-11-13  7:03       ` [ruby-core:71479] " Eric Wong
2015-12-27 22:49 ` [ruby-core:72527] " headius
2015-12-27 23:00 ` [ruby-core:72528] " headius
2015-12-27 23:40   ` [ruby-core:72529] " Eric Wong
2015-12-28  0:13 ` headius [this message]
2015-12-28  1:12   ` [ruby-core:72532] " Eric Wong
2015-12-28  0:22 ` [ruby-core:72531] " headius
2015-12-28  1:50 ` [ruby-core:72535] " headius

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