Benchmark Integer, Float and BigDecimal

ruby_bigdecimal_and_float_benchmark.rb

require 'benchmark'
require 'bigdecimal'

$CYCLE = 10_000_000

# Integer and Floats are native types
# BigDecimal is like a wrapper over a string
# Float is also a native type but is imprecise
# BigDecimal is precise and can handle arbitrary precision
# but is slower
# also check https://gist.github.com/deepak/1275050

Benchmark.bmbm do |x|
  x.report "Integer" do
    $CYCLE.times {|x| x + 1 }  
  end
  
  x.report "Float" do
    $CYCLE.times {|x| x + 0.0001 }  
  end

  # string to BigDecimal is pretty common. eg. user input on a form
  x.report "BigDecimal" do
    $CYCLE.times {|x| BigDecimal.new("#{x}.0001") }  
  end  
end

__END__

ruby 1.9.3p327 (2012-11-10 revision 37606) [x86_64-darwin10.8.0]
Rehearsal ----------------------------------------------
Integer      0.690000   0.000000   0.690000 (  0.690063)
Float        1.380000   0.000000   1.380000 (  1.381334)
BigDecimal  15.160000   0.020000  15.180000 ( 15.182957)
------------------------------------ total: 17.250000sec

                 user     system      total        real
Integer      0.730000   0.000000   0.730000 (  0.722822)
Float        1.580000   0.000000   1.580000 (  1.593262)
BigDecimal  17.590000   0.050000  17.640000 ( 17.685156)

ruby 2.0.0p0 (2013-02-24 revision 39474) [x86_64-darwin10.8.0]
Rehearsal ----------------------------------------------
Integer      0.640000   0.000000   0.640000 (  0.642389)
Float        0.910000   0.000000   0.910000 (  0.908165)
BigDecimal  19.820000   0.030000  19.850000 ( 19.857600)
------------------------------------ total: 21.400000sec

                 user     system      total        real
Integer      0.620000   0.000000   0.620000 (  0.627930)
Float        0.920000   0.000000   0.920000 (  0.923046)
BigDecimal  19.640000   0.020000  19.660000 ( 19.673304)

(on an older JDK and an older version of jruby)
jruby 1.7.1 (1.9.3p327) 2012-12-03 30a153b on Java HotSpot(TM) 64-Bit Server VM 1.6.0_43-b01-447-10M4203 [darwin-x86_64]
Rehearsal ----------------------------------------------
Integer      0.780000   0.030000   0.810000 (  0.579000)
Float        0.760000   0.050000   0.810000 (  0.666000)
BigDecimal  28.350000   1.240000  29.590000 ( 27.311000)
------------------------------------ total: 31.210000sec

                 user     system      total        real
Integer      0.710000   0.040000   0.750000 (  0.697000)
Float        0.770000   0.040000   0.810000 (  0.756000)
BigDecimal  27.480000   1.250000  28.730000 ( 27.192000)

So, if the solution is to use Integer through Money, try to add a benchmark for Money as well and see what happens. Something like:

require 'benchmark'
require 'bigdecimal'
require 'money'

$CYCLE = 10_000_00

Benchmark.bmbm do |x|
  x.report "Integer" do
    $CYCLE.times {|x| amount = x + 1; currency = "INR" }
  end

  x.report "Float" do
    $CYCLE.times {|x| amount = x + 0.0001; currency = "INR" }
  end

  x.report "Money" do
    # multiply by 100, as we have to provide paise/cents to Money
    $CYCLE.times {|x| money = Money.new((x + 0.0001)*100, "INR") }
  end

  # string to BigDecimal is pretty common. eg. user input on a form
  x.report "BigDecimal" do
    $CYCLE.times {|x| amount = BigDecimal.new("#{x}.0001"); currency = "INR" }
  end
end

__END__

Rehearsal ----------------------------------------------
Integer      0.210000   0.000000   0.210000 (  0.210774)
Float        0.340000   0.000000   0.340000 (  0.342244)
Money       32.330000   0.000000  32.330000 ( 32.412949)
BigDecimal   2.010000   0.000000   2.010000 (  2.010116)
------------------------------------ total: 34.890000sec

                 user     system      total        real
Integer      0.230000   0.000000   0.230000 (  0.229390)
Float        0.370000   0.000000   0.370000 (  0.372463)
Money       32.390000   0.000000  32.390000 ( 32.471253)
BigDecimal   1.990000   0.000000   1.990000 (  1.998426)