- Inheritance
The Benchmark module provides methods to measure and report the time used to execute Ruby code.
- Measure the time to construct the string given by the expression
"a"*1_000_000:
require 'benchmark' puts Benchmark.measure { "a"*1_000_000 }On my machine (FreeBSD 3.2 on P5, 100MHz) this generates:
1.166667 0.050000 1.216667 ( 0.571355)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 = 50000 Benchmark.bm do |x| x.report { for i in 1..n; a = "1"; end } x.report { n.times do ; a = "1"; end } x.report { 1.upto(n) do ; a = "1"; end } endThe result:
user system total real 1.033333 0.016667 1.016667 ( 0.492106) 1.483333 0.000000 1.483333 ( 0.694605) 1.516667 0.000000 1.516667 ( 0.711077) - Continuing the previous example, put a label in each report:
require 'benchmark' n = 50000 Benchmark.bm(7) do |x| x.report("for:") { for i in 1..n; a = "1"; end } 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
for: 1.050000 0.000000 1.050000 ( 0.503462)
times: 1.533333 0.016667 1.550000 ( 0.735473)
upto: 1.500000 0.016667 1.516667 ( 0.711239)
- The times for some benchmarks depend on the order in which items are run.
These differences are due to the cost of memory allocation and garbage
collection. To avoid these discrepancies, the bmbm method is provided. For example, to
compare ways to sort an array of floats:
require 'benchmark' array = (1..1000000).map { rand } Benchmark.bmbm do |x| x.report("sort!") { array.dup.sort! } x.report("sort") { array.dup.sort } endThe result:
Rehearsal ----------------------------------------- sort! 11.928000 0.010000 11.938000 ( 12.756000) sort 13.048000 0.020000 13.068000 ( 13.857000) ------------------------------- total: 25.006000sec user system total real sort! 12.959000 0.010000 12.969000 ( 13.793000) sort 12.007000 0.000000 12.007000 ( 12.791000) - Report statistics of sequential experiments with unique labels, using the
benchmark method:
require 'benchmark' n = 50000 Benchmark.benchmark(" "*7 + CAPTION, 7, FMTSTR, ">total:", ">avg:") do |x| tf = x.report("for:") { for i in 1..n; a = "1"; end } tt = x.report("times:") { n.times do ; a = "1"; end } tu = x.report("upto:") { 1.upto(n) do ; a = "1"; end } [tf+tt+tu, (tf+tt+tu)/3] endThe result:
user system total real for: 1.016667 0.016667 1.033333 ( 0.485749) times: 1.450000 0.016667 1.466667 ( 0.681367) upto: 1.533333 0.000000 1.533333 ( 0.722166) >total: 4.000000 0.033333 4.033333 ( 1.889282) >avg: 1.333333 0.011111 1.344444 ( 0.629761)
Classes & Modules
Constants
| Name | Description | |
|---|---|---|
| BENCHMARK_VERSION | = "2002-04-25" | |
| CAPTION | = Benchmark::Tms::CAPTION | The default caption string (heading above the output times). |
| FMTSTR | = Benchmark::Tms::FMTSTR | The default format string used to display times. See also Benchmark::Tms#format. |
Methods
Instance
| Visibility | Signature |
|---|---|
| public | benchmark (caption = "", label_width = nil, fmtstr = nil, *labels) {|report| ...} |
| public | bm (label_width = 0, *labels) {|report| ...} |
| public | bmbm (width = 0) {|job| ...} |
| public | measure (label = "") {|| ...} |
| public | realtime () {|| ...} |
Instance Method Detail
benchmark(caption = "", label_width = nil, fmtstr = nil, *labels) {|report| ...}
Invokes the block with a Benchmark::Report object, which may be used to collect and report on the results of individual benchmark tests. Reserves label_width leading spaces for labels on each line. Prints caption at the top of the report, and uses fmt to format each line. If the block returns an array of Benchmark::Tms objects, these will be used to format additional lines of output. If label parameters are given, these are used to label these extra lines.
Note: Other methods provide a simpler interface to this one, and are suitable for nearly all benchmarking requirements. See the examples in Benchmark, and the bm and bmbm methods.
Example:
require 'benchmark'
include Benchmark # we need the CAPTION and FMTSTR constants
n = 50000
Benchmark.benchmark(" "*7 + CAPTION, 7, FMTSTR, ">total:", ">avg:") do |x|
tf = x.report("for:") { for i in 1..n; a = "1"; end }
tt = x.report("times:") { n.times do ; a = "1"; end }
tu = x.report("upto:") { 1.upto(n) do ; a = "1"; end }
[tf+tt+tu, (tf+tt+tu)/3]
end
Generates:
user system total real
for: 1.016667 0.016667 1.033333 ( 0.485749)
times: 1.450000 0.016667 1.466667 ( 0.681367)
upto: 1.533333 0.000000 1.533333 ( 0.722166)
>total: 4.000000 0.033333 4.033333 ( 1.889282)
>avg: 1.333333 0.011111 1.344444 ( 0.629761)
bm(label_width = 0, *labels) {|report| ...}
A simple interface to the benchmark method, bm is generates sequential reports with labels. The parameters have the same meaning as for benchmark.
require 'benchmark'
n = 50000
Benchmark.bm(7) do |x|
x.report("for:") { for i in 1..n; a = "1"; end }
x.report("times:") { n.times do ; a = "1"; end }
x.report("upto:") { 1.upto(n) do ; a = "1"; end }
end
Generates:
user system total real
for: 1.050000 0.000000 1.050000 ( 0.503462)
times: 1.533333 0.016667 1.550000 ( 0.735473)
upto: 1.500000 0.016667 1.516667 ( 0.711239)
bmbm(width = 0) {|job| ...}
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! 11.928000 0.010000 11.938000 ( 12.756000)
sort 13.048000 0.020000 13.068000 ( 13.857000)
------------------------------- total: 25.006000sec
user system total real
sort! 12.959000 0.010000 12.969000 ( 13.793000)
sort 12.007000 0.000000 12.007000 ( 12.791000)
bmbm yields a Benchmark::Job object and returns an array of Benchmark::Tms objects.
measure(label = "") {|| ...}
Returns the time used to execute the given block as a Benchmark::Tms object.
realtime() {|| ...}
Returns the elapsed real time used to execute the given block.