Ruby Benchmark: Counting the number of lines of a file

line_count_benchmark.rb

# gem install benchmark-ips

require "benchmark/ips"

path = "path/to/a_big_file"

Benchmark.ips do |x|
  x.report("read + each_line") { File.read(path).each_line.count }
  x.report("open + each_line") { File.open(path, "r").each_line.count }
  x.report("open + readlines") { File.open(path, "r").readlines.length }
  x.report("foreach + count")  { File.foreach(path).count }
  x.report("foreach + inject") { File.foreach(path).inject(0) {|count, line| count + 1 } }
  x.report("foreach")          { count = 0; File.foreach(path) { count += 1}; count }
  x.report("wc")               { `wc -l < "#{path}"`.to_i }
  x.compare!
end

result.txt

Warming up --------------------------------------
    read + each_line     1.000  i/100ms
    open + each_line     1.000  i/100ms
    open + readlines     1.000  i/100ms
     foreach + count     1.000  i/100ms
    foreach + inject     1.000  i/100ms
             foreach     1.000  i/100ms
                  wc     1.000  i/100ms
Calculating -------------------------------------
    read + each_line      1.341  (± 0.0%) i/s -      7.000  in   5.231149s
    open + each_line      1.730  (± 0.0%) i/s -      9.000  in   5.206121s
    open + readlines      1.402  (± 0.0%) i/s -      7.000  in   5.025912s
     foreach + count      1.598  (± 0.0%) i/s -      9.000  in   5.635684s
    foreach + inject      1.468  (± 0.0%) i/s -      8.000  in   5.453793s
             foreach      1.486  (± 0.0%) i/s -      8.000  in   5.386620s
                  wc      3.446  (± 0.0%) i/s -     18.000  in   5.226358s

Comparison:
                  wc:        3.4 i/s
    open + each_line:        1.7 i/s - 1.99x  slower
     foreach + count:        1.6 i/s - 2.16x  slower
             foreach:        1.5 i/s - 2.32x  slower
    foreach + inject:        1.5 i/s - 2.35x  slower
    open + readlines:        1.4 i/s - 2.46x  slower
    read + each_line:        1.3 i/s - 2.57x  slower