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Benchmark.bmbm
# File tmp/rubies/ruby-3.0.5/lib/benchmark.rb, line 246
def bmbm(width = 0) # :yield: job
job = Job.new(width)
yield(job)
width = job.width + 1
sync = STDOUT.sync
STDOUT.sync = true
# rehearsal
puts 'Rehearsal '.ljust(width+CAPTION.length,'-')
ets = job.list.inject(Tms.new) { |sum,(label,item)|
print label.ljust(width)
res = Benchmark.measure(&item)
print res.format
sum + res
}.format("total: %tsec")
print " #{ets}\n\n".rjust(width+CAPTION.length+2,'-')
# take
print ' '*width + CAPTION
job.list.map { |label,item|
GC.start
print label.ljust(width)
Benchmark.measure(label, &item).tap { |res| print res }
}
ensure
STDOUT.sync = sync unless sync.nil?
end
Sometimes benchmark results are skewed because code executed earlier encounters different garbage collection overheads than that run later. bmbm attempts to minimize this effect by running the tests twice, the first time as a rehearsal in order to get the runtime environment stable, the second time for real. GC.start is executed before the start of each of the real timings; the cost of this is not included in the timings. In reality, though, there’s only so much that bmbm can do, and the results are not guaranteed to be isolated from garbage collection and other effects.
Because bmbm takes two passes through the tests, it can calculate the required label width.
require 'benchmark' array = (1..1000000).map { rand } Benchmark.bmbm do |x| x.report("sort!") { array.dup.sort! } x.report("sort") { array.dup.sort } end
Generates:
Rehearsal -----------------------------------------
sort! 1.440000 0.010000 1.450000 ( 1.446833)
sort 1.440000 0.000000 1.440000 ( 1.448257)
-------------------------------- total: 2.890000sec
user system total real
sort! 1.460000 0.000000 1.460000 ( 1.458065)
sort 1.450000 0.000000 1.450000 ( 1.455963)
bmbm yields a Benchmark::Job object and returns an array of Benchmark::Tms objects.