simplebench

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simplebench

npm install simplebench

simplebench is a tail call optimized benchmarking tool for asynchronous and synchronous microbenchmarking. This library seeks to minimize test overhead ensuring that the proper result is seen. In other libraries the cost of doing the tests is muddied into the performance results making the results unreliable.

The way simplebench operates is that it calls each test in your suite as many times as it can in a given duration. Each call is executed one after the other. If the call completes after the duration expires, it is not counted. From there we can determine ops/sec and compare the different tests to determine a winner. It is best to ensure that the duration is long enough that numerous iterations (>1000) are able to complete to ensure a reasonable sample size.

// /examples/example_cli.js
var arr = [1,2,3,4,5];
var suite = new simplebench.Suite();
suite.add("forEach", function(done) {
    arr.forEach(function(val) {});
    return done();
});
 
suite.add("for", function(done) {
    for(var i = 0; i < arr.length; i++) {
        var val = arr[i];
    }
    return done();
});
: ./bin/simplebench ./examples/example_cli.js
for - count: 2391635, ops/sec: 2391635
forEach - count: 1477829, ops/sec: 1477829

: ./bin/simplebench ./examples/example_cli.js --compare
Winner - for

for - count: 2381534, ops/sec: 2381534
forEach - count: 1510180, ops/sec: 1510180, diff: -36.59%

Command Line Interface

The easiest way to use simplebench is via the cli similar to Mocha. Create a suite file, execute it.

You can pass arguments to the cli that match 1 to 1 to the arguments of the Suite constructor. See the constructor documentation below for the available options.

Generally there are two types of test files you will run. One is a comparison of multiple ways of doing the same task, such as for vs forEach vs for in. The other is snapshot where you are simply benchmarking certain functions and how long they take today. Usually used when comparing the same functions to a time in the future with a different Node version, or after optimizations have been made.

# run a comparison benchmark
simplebench example.js --compare

# run a bunchmark, don't compare, save results. Used sometimes when comparing different Node versions or saving benchmarks for comparison to future versions of code.
simplebench example.js --save

# run a benchmmark, compare and save
simplebench example.js --save --compare

# --trace-inlining, --trace-deopt, --trace-opt, and --trace-gc can be passed along as well to debug v8 optimization
simplebench example.js --trace-opt --trace-deopt --trace-inlining

As a node package

If you are using simplebench as a Node package, simply require it in and follow the steps below.

// ./examples/example_node.js
var simplebench = require("../index.js"); // change this path to "simplebench" for your usecase
 
var arr = [1,2,3,4,5];
var suite = new simplebench.Suite({ compare : true });
suite.add("forEach", function(done) {
    arr.forEach(function(val) {});
    return done();
});
 
suite.add("for", function(done) {
    for(var i = 0; i < arr.length; i++) {
        var val = arr[i];
    }
    return done();
});
 
suite.run(function(err, results) {
    if (err) { throw err; }
    
    suite.report(results);
});
// execute
: node --harmony --harmony-tailcalls --use-strict ./examples/example_node.js
Winner - for

Results:
for - count: 2427560, ops/sec: 2427560
forEach - count: 1491169, ops/sec: 1491169, diff: -38.57%

As of Node 7.10.0, in order to enable tail call optimization you will need to start your node file with --harmony --harmony-tailcalls. If you do not utilize "use strict" in your test file, you can also start with --use-strict to enable it process-wide. If both settings are not enabled, it will not be possible to utilize TCO and you may need to use the Suite argument bounce to avoid max call stack errors.

// execute
: node --harmony --harmony-tailcalls --use-strict example.js
Winner - for

Results:
for - count: 2427560, ops/sec: 2427560
forEach - count: 1491169, ops/sec: 1491169, diff: -38.57%

Documentation

Suite

The suite is the primary mechanism you will use for creating comparison tests.

Suite constructor(args)

Create a new test suite with specific arguments.

  • duration - number - default 1000 (1 second) - Duration in milliseconds for each test in the suite to run.
  • bounce - boolean - default false - Whether to bounce off the event loop. For functions which are not TCO, if they do not bounce off the loop after X iterations, they can stack overflow. The preferred option is making it TCO. If that's not available, then you can enable bounce.
  • bounceEvery - number - default 1000 - After X iterations it will bounce off the event loop. Needed when TCO cannot be utilized.
  • compare - boolean - default false - Compare the results from the different tests.
  • save - boolean - default false - Save the results of the test to a file when utilized from the CLI
  • savePath - string - default process.cwd() - The root path to save test files to. Defaults to the current working directory.
  • saveFileRoot - string - The filename used for creating the timestamped save file. It defaults to the name of the benchmark file or "simplebench" if nothing is passed.
  • saveFilename - string - The full name of the file to save. By default it will be saveFileRoot + (timestamp).json.
  • logArgs - boolean - The constructor will output the args are it's interpretting them. Used if curious how it's interpretting command line arguments.
var suite = new simplebench.Suite(); // default args
var suite = new simplebench.Suite({ bounce : true, bounceEvery : 100 }); // bounce off event loop every 100 iterations
var suite = new simplebench.Suite({ duration : 100 * 1000 }); // each test in the suite will run for 100ms

Suite.prototype.add(name, cb)

Add a test to the suite. The same name can only occur in each suite once.

  • name - string - The name of the test
  • cb - function - A function which will receive a done function. Call it upon test completion.

Suite.prototype.group(name, cb)

Add a group to a suite. All tests declared within the group will be compared against each other, but not against tests in other groups. Used for testing multiple scenarios.

An example of using this would be if you were testing array loop methods, and you wanted to do comparisons of large arrays and small arrays. In that case it's obviously invalid to compare the looping of a large array vs a small array. So you'd group the large tests into a group and the small tests into a group.

When using groups, all tests in your file must be within a group.

  • name - string - The name of the test
  • cb - function - A function which is called immediately, in which you would suite.add() the tests for that group.
// when comparing, each test is only compared with the tests in it's  test1 and test2 will be compared, and test3 and test4 will be compared but test1 will not be compared to test3 or test4
suite.group("group1", function() {
    suite.add("test1", function(done) {
    
    });
    
    suite.add("test2", function(done) {
        
    });
});
 
suite.group("group2", function() {
    suite.add("test3", function(done) {
    
    });
    
    suite.add("test4", function(done) {
        
    });
});

Suite.prototype.run(cb)

Run the test suite and determine the winner.

  • cb - function - A function which will receive err, results. The results object is commonly passed to suite.report(results). It can also be manually reported on.

Suite.prototype.skip

Skip a test or group from executing.

// will not execute this test
suite.skip.add("test1", function(done) {
 
});
 
// will not execute this group
suite.skip.group("group1", function(done) {
 
});

Suite.prototype.report(results)

Used to output the results object in a human readable format.

  • results - object - Output the results object.

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