bench_reload.rb

require 'concurrent/atomic/read_write_lock'
require 'benchmark/ips'
require 'active_support/core_ext/string'
rw = Concurrent::ReadWriteLock.new

Benchmark.ips do |x|
  x.report("with_read_lock") do
    rw.with_read_lock do
      Math.sqrt(4)
    end
  end
  x.report("with_constantize") do
    'Math'.constantize.sqrt(4)
  end
  x.report("w/o_read_lock") do
    Math.sqrt(4)
  end
end

      with_read_lock      1.220M (± 0.8%) i/s -      6.226M in   5.102049s
    with_constantize      6.494M (± 1.5%) i/s -     32.889M in   5.065326s
       w/o_read_lock     20.521M (± 0.6%) i/s -    104.535M in   5.094169s