test/parallel/test-stream-writable-samecb-singletick.js

'use strict';
const common = require('../common');
const { Console } = require('console');
const { Writable } = require('stream');
const async_hooks = require('async_hooks');

// Make sure that repeated calls to console.log(), and by extension
// stream.write() for the underlying stream, allocate exactly 1 tick object.
// At the time of writing, that is enough to ensure a flat memory profile
// from repeated console.log() calls, rather than having callbacks pile up
// over time, assuming that data can be written synchronously.
// Refs: https://github.com/nodejs/node/issues/18013
// Refs: https://github.com/nodejs/node/issues/18367

const checkTickCreated = common.mustCall();

async_hooks.createHook({
  init(id, type, triggerId, resource) {
    if (type === 'TickObject') checkTickCreated();
  }
}).enable();

const console = new Console(new Writable({
  write: common.mustCall((chunk, encoding, cb) => {
    cb();
  }, 100)
}));

for (let i = 0; i < 100; i++)
  console.log(i);