v8: refactor the v8 module

[jasnell]

• Use the more efficient module.exports = {} pattern,
• Refactor the imports from bindings and requires
• Add a benchmark

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines

Affected core subsystem(s)

v8

[vsemozhetbyt]

If I understand the guide right, this should be a property of the third argument (options). And flags do not vary, so empty flag seems to be useless. However, I may miss something.

[vsemozhetbyt]

Also I am not sure if the '--ignition --turbo' should be '--ignition', '--turbo'

[jasnell]

Setting the flags like this runs the benchmark with two separate configurations, one with --ignition --turbo and the other without flags. I wasn't sure myself but this definitely worked when I ran it like this :-)

[vsemozhetbyt]

Are you sure the flags are really set, not only displayed in the config list? I've added a debug log:

'use strict';

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

const bench = common.createBenchmark(main, {
  method: [
    'getHeapStatistics',
    'getHeapSpaceStatistics'
  ],
  n: [1e6],
  flags: ['--ignition --turbo', '']
});

function main(conf) {
  console.log(process.execArgv);
  const n = +conf.n;
  const method = conf.method;
  var i = 0;
  bench.start();
  for (; i < n; i++)
    v8[method]();
  bench.end(n);
}

[]
v8\get-stats.js flags="--ignition --turbo" n=1000000 method="getHeapStatistics": 1,476,245.8999447592
[]
v8\get-stats.js flags="" n=1000000 method="getHeapStatistics": 1,455,785.4873297967
[]
v8\get-stats.js flags="--ignition --turbo" n=1000000 method="getHeapSpaceStatistics": 2,515,738.0104498775
[]
v8\get-stats.js flags="" n=1000000 method="getHeapSpaceStatistics": 2,505,423.9547382533

[vsemozhetbyt]

Compare:

'use strict';

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

const bench = common.createBenchmark(main, {
  method: [
    'getHeapStatistics',
    'getHeapSpaceStatistics'
  ],
  n: [1e6],
}, { flags: ['--ignition', '--turbo'] });

function main(conf) {
  console.log(process.execArgv);
  const n = +conf.n;
  const method = conf.method;
  var i = 0;
  bench.start();
  for (; i < n; i++)
    v8[method]();
  bench.end(n);
}

[ '--ignition', '--turbo' ]
v8\get-stats.js n=1000000 method="getHeapStatistics": 1,267,677.6893168623
[ '--ignition', '--turbo' ]
v8\get-stats.js n=1000000 method="getHeapSpaceStatistics": 1,821,113.6853929006

[vsemozhetbyt]

It seems this is a design that can be improved. Currently, the key flags in configs has no automatic impact, while the same flag in options can not vary between runs.

cc @nodejs/performance, @nodejs/benchmarking, @mscdex

[jasnell]

I'll just back the flags bit out of this particular change to keep it from holding this up at all, but big +1 on refactoring this generally.

[mscdex]

I would actually prefer flags in the config object to not have any automagic behavior. It should retain its 'config' meaning (allowing it to be specified on the command line as a regular benchmark option).

[vsemozhetbyt]

Yes, I did not propose the automatic behavior for this key in config. I meant that may be an easier way to vary execArgv between runs can be supported.

[joyeecheung]

Yes, the flags in the options is applied to all runs...to compare the performance under different flags I would suggest something like

const bench = common.createBenchmark(main, {
  method: [
    'getHeapStatistics',
    'getHeapSpaceStatistics'
  ],
  n: [1e6],
  pipeline: ['new', 'old']
});

function main(conf) {
  if (conf.pipeline === 'new') {
    v8.setFlagsFromString('--ignition');
    v8.setFlagsFromString('--turbo')
  }
}

Unless we have to turn on the flag during bootstrapping..in that case we do need to add special support in the benchmark suite.

[jasnell]

@vsemozhetbyt ... updated! PTAL

[jasnell]

CI: https://ci.nodejs.org/job/node-test-pull-request/7721/

[joyeecheung]

Replied here since the review above is folded..

Yes, the `flags` in the `options` is applied to all runs...to compare the performance under different flags I would suggest something like

const bench = common.createBenchmark(main, {
  method: [
    'getHeapStatistics',
    'getHeapSpaceStatistics'
  ],
  n: [1e6],
  pipeline: ['new', 'old']
});

function main(conf) {
  if (conf.pipeline === 'new') {
    v8.setFlagsFromString('--ignition');
    v8.setFlagsFromString('--turbo')
  }
}

Unless we have to turn on the flag during bootstrapping..in that case we do need to add special support in the benchmark suite.

[jasnell]

Landed in bed4612 and 1052383