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benchmark: util._extend vs object.assign #7255

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benchmark: util._extend vs object.assign #7255

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benchmark: `util._extend` vs `object.assign`
suryagh Jun 10, 2016
100a8be
benchmark: review comments
suryagh Jun 11, 2016
a3daa3b
benchmark: use proxy object as target
suryagh Jun 11, 2016
0e9260f
benchmark: use proxy object as target
suryagh Jun 20, 2016
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40 changes: 40 additions & 0 deletions benchmark/misc/util-extend-vs-object-assign.js
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'use strict';

const common = require('../common.js');
const util = require('util');
const v8 = require('v8');

const bench = common.createBenchmark(main, {
type: ['util._extend', 'Object.assign',
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@mscdex mscdex Jun 10, 2016 •
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I think these can be shortened down to just extend (or _extend) and assign.

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@suryagh suryagh Jun 11, 2016

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Done.

'util._extend', 'Object.assign'],
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@mscdex mscdex Jun 10, 2016

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Why are there duplicates?

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@suryagh suryagh Jun 11, 2016

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Removed.

n: [10e4]
});

function main(params) {
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@mscdex mscdex Jun 10, 2016

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minor nit: it's probably better to keep with the same variable naming as other benchmarks, in other words, s/params/conf/

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@suryagh suryagh Jun 11, 2016

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Done.

let fn;
const n = params.n | 0;
let v8command;

if (params.type == 'util._extend') {
fn = util._extend;
v8command = '%OptimizeFunctionOnNextCall(util._extend)';
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@mscdex mscdex Jun 10, 2016 •
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I don't know exactly how %OptimizeFunctionOnNextCall() works/is implemented, but I wonder if util._extend here should instead be fn?

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@suryagh suryagh Jun 11, 2016

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I think this is the right way. It will get eval to the correct function reference by v8.


} else if (params.type == 'Object.assign') {
fn = Object.assign;
//Object.assign is built-in, cannot be optimized
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@mscdex mscdex Jun 20, 2016

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Space needed after //.

v8command = '';
}

// Force-optimize the method to test so that the benchmark doesn't
// get disrupted by the optimizer kicking in halfway through.
for (let i = 0; i < params.type.length * 10; i += 1)
fn({}, process.env);

v8.setFlagsFromString('--allow_natives_syntax');
eval(v8command);

bench.start();
for (let i = 0; i < n; i += 1)
fn({}, process.env);
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@mscdex mscdex Jun 10, 2016 •
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I'm not sure if this is the best test or not. At the very least, how does this compare with just using a same, empty, frozen object instead of a new {} every time? For example:

var obj = {};
Object.freeze(obj);

bench.start();
for (var i = 0; i < n; i += 1)
  fn(obj, process.env);
bench.end(n);

Also, on an unrelated note, it's best to avoid using let in loops like that until v8 optimizes that use case. It probably matters less on benchmarks like this, but hey, the sooner the benchmark finishes the better, right? ;-)

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@suryagh suryagh Jun 11, 2016

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Both assign and _extend would throw exception if the first argument is frozen, since they modify it. However, used a pre-defined obj as you recommended above.

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@mscdex mscdex Jun 11, 2016 •
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Ok, how about using a Proxy then?:

var obj = new Proxy({}, { set: function(a, b, c) { return true; } });

bench.start();
for (var i = 0; i < n; i += 1)
  fn(obj, process.env);
bench.end(n);

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@suryagh suryagh Jun 11, 2016

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Done

bench.end(n);
}