Ruby speed & memory bench: Array#compact vs nil check

memory.rb

# frozen_string_literal: true

require "pathname"
require "memory_profiler"

class Env
  def load!(*)
  end
end

class Loader
  def initialize
    @environment = "development"
    @root = Pathname.new(Dir.pwd)
    @env = Env.new
  end

  def load_with_compact
    [
      root.join(".env.#{environment}.local"),
      (root.join(".env.local") unless environment == "test"),
      root.join(".env.#{environment}"),
      root.join(".env")
    ].compact.each do |path|
      env.load!(path) if path.exist?
    end
  end

  def load_with_nil_check
    [
      root.join(".env.#{environment}.local"),
      (root.join(".env.local") unless environment == "test"),
      root.join(".env.#{environment}"),
      root.join(".env")
    ].each do |path|
      env.load!(path) if path&.exist?
    end
  end

  private

  attr_reader :environment, :root
end

loader = Loader.new

# report = MemoryProfiler.report do
#   10_000.times do
#     loader.load_with_compact
#   end
# end

# report.pretty_print

report = MemoryProfiler.report do
  10_000.times do
    loader.load_with_nil_check
  end
end

report.pretty_print

__END__

#load_with_compact

Total allocated: 61761558 bytes (1400010 objects)
Total retained:  558 bytes (2 objects)

#load_with_nil_check

Total allocated: 61041558 bytes (1390010 objects)
Total retained:  558 bytes (2 objects)

speed.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

require "benchmark/ips"
require "pathname"

class Env
  def load!(*)
  end
end

class Loader
  def initialize
    @environment = "development"
    @root = Pathname.new(Dir.pwd)
    @env = Env.new
  end

  def load_with_compact
    [
      root.join(".env.#{environment}.local"),
      (root.join(".env.local") unless environment == "test"),
      root.join(".env.#{environment}"),
      root.join(".env")
    ].compact.each do |path|
      env.load!(path) if path.exist?
    end
  end

  def load_with_nil_check
    [
      root.join(".env.#{environment}.local"),
      (root.join(".env.local") unless environment == "test"),
      root.join(".env.#{environment}"),
      root.join(".env")
    ].each do |path|
      env.load!(path) if path&.exist?
    end
  end

  private

  attr_reader :environment, :root
end

loader = Loader.new

Benchmark.ips do |x|
  x.report("compact") { loader.load_with_compact }
  x.report("nil check") { loader.load_with_nil_check }
  x.compare!
end

__END__
Result:

Warming up --------------------------------------
             compact     2.071k i/100ms
           nil check     2.097k i/100ms
Calculating -------------------------------------
             compact     20.925k (± 6.1%) i/s -    105.621k in   5.069481s
           nil check     21.377k (± 3.0%) i/s -    106.947k in   5.007818s

Comparison:
           nil check:    21377.2 i/s
             compact:    20925.4 i/s - same-ish: difference falls within error

Ruby:

    ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-darwin16]

Hardware:

    Hardware Overview:

      Model Name: MacBook Pro
      Model Identifier: MacBookPro12,1
      Processor Name: Intel Core i7
      Processor Speed: 3,1 GHz
      Number of Processors: 1
      Total Number of Cores: 2
      L2 Cache (per Core): 256 KB
      L3 Cache: 4 MB
      Memory: 16 GB
      Boot ROM Version: 184.0.0.0.0
      SMC Version (system): 2.28f7

Software:

    System Software Overview:

      System Version: macOS 10.12.6 (16G2016)
      Kernel Version: Darwin 16.7.0
      Time since boot: 8 days 16:40