`str.count("\n")` is 1.3-170 times faster than `str.lines.count` or `str.each_line.count` depending on the string size

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
45/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
ruby
Domain
performance

Research direction

Start by inspecting fast-ruby's existing benchmark organization and compare it with the benchmark code shown in tmp/string_count_benchmark.rb. Add the String line-count comparison in the repository's established format, then run the relevant benchmark or project checks to confirm the new entry works.

Written by the indexing model from the issue text.

Description

str.count("\n") is 1.3-170 times faster than str.lines.count or str.each_line.count (ref: https://serpapi.com/blog/lines-count-failed-deployments/). The speed difference grows with the lines count.

$ ruby tmp/string_count_benchmark.rb
Warming up --------------------------------------
  String#count('\n')    86.000  i/100ms
   String#lines.size     1.000  i/100ms
  String#lines.count     1.000  i/100ms
String#each_line.count
                         1.000  i/100ms
Calculating -------------------------------------
  String#count('\n')    771.031  (± 6.6%) i/s -      3.870k in   5.041849s
   String#lines.size      4.785  (± 0.0%) i/s -     24.000  in   5.037242s
  String#lines.count      4.513  (± 0.0%) i/s -     23.000  in   5.112095s
String#each_line.count
                          4.763  (± 0.0%) i/s -     24.000  in   5.075882s

Comparison:
  String#count('\n'):      771.0 i/s
   String#lines.size:        4.8 i/s - 161.12x  (± 0.00) slower
String#each_line.count:        4.8 i/s - 161.87x  (± 0.00) slower
  String#lines.count:        4.5 i/s - 170.86x  (± 0.00) slower

Benchmark code:

require "benchmark/ips"

HTML = "\nruby\n" * 1024 * 1024

def fastest
  HTML.count("\n")
end

def faster
  HTML.each_line.count
end

def fast
  HTML.lines.length
end

def slow
  HTML.lines.size
end

Benchmark.ips do |x|
  x.report("String#count('\\n')")     { fastest }
  x.report("String#lines.size")       { faster  }
  x.report("String#lines.count")      { fast    }
  x.report("String#each_line.count")  { slow    }
  x.compare!
end

I'd like to add this benchmark to fast-ruby. Wdyt?

Based on our updates to the @guilhermesimoes' very helpful gist: https://gist.github.com/guilhermesimoes/d69e547884e556c3dc95?permalink_comment_id=4687645#gistcomment-4687645

Dominant language
Ruby
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