nodejs/node#17027

with-promise.js

const fs = require('fs');
const async_hooks = require('async_hooks');

let indent = 0;
async_hooks.createHook({
  init(asyncId, type, triggerAsyncId) {
    const eid = async_hooks.executionAsyncId();
    const indentStr = ' '.repeat(indent);
    fs.writeSync(
      1,
      `${indentStr}${type}(${asyncId}):` +
      ` trigger: ${triggerAsyncId} execution: ${eid}\n`);
  },
  before(asyncId) {
    const indentStr = ' '.repeat(indent);
    fs.writeSync(1, `${indentStr}before:  ${asyncId}\n`);
    indent += 2;
  },
  after(asyncId) {
    indent -= 2;
    const indentStr = ' '.repeat(indent);
    fs.writeSync(1, `${indentStr}after:   ${asyncId}\n`);
  },
  destroy(asyncId) {
    const indentStr = ' '.repeat(indent);
    fs.writeSync(1, `${indentStr}destroy: ${asyncId}\n`);
  },
  promiseResolve(asyncId) {
    const indentStr = ' '.repeat(indent);
    fs.writeSync(1, `${indentStr}promiseResolve: ${asyncId}\n`);
  },
}).enable();




var makePromise = timeout => {
	return new Promise(done => {
		setTimeout(() => {
			console.log('done');
			done();
		}, timeout);
	});
};

makePromise(3000).then(() => {
	fs.writeFile('bar.txt', 'baz', { encoding: 'utf8' }, (e) => {
		if(e) {
			console.log(e);
		}
		else {
			console.log('finished');
		}
	});
});