node file sync test

test.js

const fs = require('fs');

const startTime = Date.now();
console.log('start at', startTime);

setTimeout(() => {
  const endTime = Date.now();
  console.log('0.01 sec later', endTime);
  console.log(endTime - startTime)
}, 10)


const filePath = '/Users/kaze/Code/js/归档.zip'

if (process.argv[2] === 'sync') {
  const readFileStart = Date.now();
  console.log('read file start', readFileStart);
  fs.readFileSync(filePath)
  const readFileEnd = Date.now();
  console.log('read file end', readFileEnd);
  console.log('read file during', readFileEnd - readFileStart);
} else {
  fs.readFile(filePath, (err, file) => {})
}

/Users/kaze/Code/js/归档.zip is a file cost 100ms for i/o reading

The response is

node test.js  sync
start at 1503807147461
read file start 1503807147480
read file end 1503807147774
read file during 294
0.01 sec later 1503807147775
314

node test.js      
start at 1503807150126
0.01 sec later 1503807150154
28

So, readFileSync will block other async tasks response time