Bug #12074: [PERF] bm_app_erb.rb slower

• Status: Closed
• Assignee: k0kubun (Takashi Kokubun)
• Target version: -
• ruby -v: ruby 2.4.0dev (2016-01-02 trunk 53412)
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN

[tgxworld (Guo Xiang Tan)]

Hi I'm noticing a regression on RubyBench for bm_app_erb.rb

http://rubybench.org/ruby/ruby/commits?result_type=app_erb&display_count=2000

Narrowed down to https://github.com/ruby/ruby/commit/32b4a8b

Results on my local machine confirms it as well:

total: 2 trial(s) (2 trial(s) for 1 benchmark(s))
..
-----------------------------------------------------------
benchmark results:
Execution time (sec)
name  ruby 2.4.0dev (2016-01-02 trunk 53411) [x86_64-linux]
Posting results to Web UI....
app_erb 0.614

total: 2 trial(s) (2 trial(s) for 1 benchmark(s))
..
-----------------------------------------------------------
benchmark results:
Execution time (sec)
name  ruby 2.4.0dev (2016-01-02 trunk 53412) [x86_64-linux]
Posting results to Web UI....
app_erb 0.911

Let me know if I can provide more information :)

[k0kubun (Takashi Kokubun)]

• Assignee set to k0kubun (Takashi Kokubun)

[k0kubun (Takashi Kokubun)]

• Status changed from Open to Closed

Applied in changeset trunk|r58842.

---

erb.rb: Skip creating regexp

if stags and etags are not changed from default.

:putobject insn (of regexp) will be used instead of :toregexp insn.
This means that the regexp won't be compiled for every
SimpleScanner#scan call.

It may not be a good idea to apply this kind of optimization for all cases.
But I applied this because it is default scanner and used frequently and has
relatively large impact for benchmark like this:

• Before
  app_erb 1.023

• After
  app_erb 0.781

This commit fixes only the bottleneck of performance regression introduced
in r53412. For maintainability, I won't fix other small regressions like
additional overhead of method calls.

[ruby-core:73820] [Bug #12074]