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Revision dce4a3f5

Added by watson1978 (Shizuo Fujita) about 6 years ago

Improve CSV performance

If it will not use special variables (like $1, $&, $`...),
it can improve the performance by using Regexp#match? or String#match? instead of Regexp#=~ or String#=~.

This patch is same idea as https://github.com/ruby/ruby/pull/1836

[Fix GH-1842]

Environment

  • OS : Ubuntu 17.10
  • Compiler : gcc version 7.2.0
  • CPU : Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
  • Memory : 16 GB

TL;DR

Methods Before After Speed up
CSV.foreach 44.825 48.201 7.5%
CSV#shift 45.200 49.584 9.7%
CSV.read 42.968 46.853 9.0%
CSV.table 10.933 11.277 3.1%

Before

Calculating -------------------------------------
         CSV.foreach     44.825  (± 0.0%) i/s -    228.000  in   5.086576s
           CSV#shift     45.200  (± 0.0%) i/s -    228.000  in   5.044297s
            CSV.read     42.968  (± 0.0%) i/s -    216.000  in   5.027504s
           CSV.table     10.933  (± 0.0%) i/s -     55.000  in   5.031098s

After

Calculating -------------------------------------
         CSV.foreach     48.201  (± 0.0%) i/s -    244.000  in   5.062256s
           CSV#shift     49.584  (± 0.0%) i/s -    248.000  in   5.001652s
            CSV.read     46.853  (± 0.0%) i/s -    236.000  in   5.037044s
           CSV.table     11.277  (± 0.0%) i/s -     57.000  in   5.054694s

Benchmark code

require 'csv'
require 'benchmark/ips'

CSV.open("/tmp/file.csv", "w") do |csv|
  csv << ["player", "gameA", "gameB"]
  1000.times do
    csv << ['"Alice"', "84.0", "79.5"]
    csv << ['"Bob"', "20.0", "56.5"]
  end
end

Benchmark.ips do |x|
  x.report "CSV.foreach" do
    CSV.foreach("/tmp/file.csv") do |row|
    end
  end

  x.report "CSV#shift" do
    CSV.open("/tmp/file.csv") do |csv|
      while line = csv.shift
      end
    end
  end

  x.report "CSV.read" do
    CSV.read("/tmp/file.csv")
  end

  x.report "CSV.table" do
    CSV.table("/tmp/file.csv")
  end
end

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62806 b2dd03c8-39d4-4d8f-98ff-823fe69b080e