module Benchmark

Overview

The Benchmark module provides methods for benchmarking Crystal code, giving detailed reports on the time taken for each task.

Measure the number of iterations per second of each task

require "benchmark"
Benchmark.ips do |x|
  x.report("short sleep")   { sleep 0.01  }
  x.report("shorter sleep") { sleep 0.001 }
end

This generates the following output:

  short sleep    91.82 (±  1.11)  8.72× slower
shorter sleep   800.98 (±  4.72)       fastest

Benchmark::IPS defaults to 2 seconds of warmup time and 5 seconds of calculation time. This can be configured:

Benchmark.ips(warmup: 4, calculation: 10) do |x|
  # …
end

Make sure to always benchmark code by compiling with the --release flag.

Measure the time to construct the string given by the expression: `"a"*1_000_000_000`

require "benchmark"

puts Benchmark.measure { "a"*1000000000 }

This generates the following output:

 0.190000   0.220000   0.410000 (  0.420185)

This report shows the user CPU time, system CPU time, the sum of the user and system CPU times, and the elapsed real time. The unit of time is seconds.

Do some experiments sequentially using the `#bm` method:

require "benchmark"

n = 5000000
Benchmark.bm do |x|
 x.report("times:") { n.times do ; a = "1"; end }
 x.report("upto:") { 1.upto(n) do ; a = "1"; end }
end

The result:

           user     system      total        real
times:   0.010000   0.000000   0.010000 (  0.008976)
upto:    0.010000   0.000000   0.010000 (  0.010466)

Make sure to always benchmark code by compiling with the --release flag.

Extended Modules

Benchmark

Defined in:

Instance Method Summary

#bm(&block)
Main interface of the Benchmark module.
#ips(calculation = 5, warmup = 2, &block)
Instruction per second interface of the Benchmark module.
#measure(label = "", &block) : BM::Tms
Returns the time used to execute the given block.
#realtime(&block) : TimeSpan
Returns the elapsed real time used to execute the given block.

Instance Method Detail

def bm(&block)

Main interface of the Benchmark module. Yields a Job to which one can report the benchmarks. See the module's description.

def ips(calculation = 5, warmup = 2, &block)

Instruction per second interface of the Benchmark module. Yields a Job to which one can report the benchmarks. See the module's description.

The optional parameters calculation and warmup set the duration of those stages in seconds. For more detail on these stages see Benchmark::IPS.

def measure(label = "", &block) : BM::Tms

Returns the time used to execute the given block.

def realtime(&block) : TimeSpan

Returns the elapsed real time used to execute the given block.

Benchmark.realtime { "a" * 100000 } #=> 00:00:00.0005840