From: normalperson@...
Date: 2015-07-07T21:59:47+00:00
Subject: [ruby-core:69892] [Ruby trunk - Feature #11339] [Open] [PATCH] io.c: avoid kwarg parsing in C API

Issue #11339 has been reported by Eric Wong.

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Feature #11339: [PATCH] io.c: avoid kwarg parsing in C API
https://bugs.ruby-lang.org/issues/11339

* Author: Eric Wong
* Status: Open
* Priority: Normal
* Assignee: 
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~~~
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:

[["io_nonblock_noex",
  [[2.5436805468052626, 2.5724728293716908, 2.4915440678596497],
   [2.478000810369849, 2.4285155069082975, 2.462410459294915]]],
 ["io_nonblock_noex2",
  [[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.
~~~


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


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