Node.js process.nextTick still blocking server from getting requests

Question

I got this piece of code :

 import http from 'http'; function compute() { let [sum, i] = [1, 1]; while (i<1000000000) { 5*2 i++; } console.log("good"); process.nextTick(compute); } http.createServer((request, response) => { response.writeHead(200, {'Content-Type': 'text/plain'}); response.end('Hello World'); }).listen(5000, '127.0.0.1'); http.request({hostname: '127.0.0.1', port: 5000}, (response) => { console.log("here !"); }).end(); compute(); 

the output for that is always : "good, "good" ... and the HTTP request didn't get called. I thought that process.nextTick should solve that problem, but server is still blocked. Why ? How can I fix it ?

Answer 1

Instead of process.nextTick rather use set setImmediate . Callbacks passed to nextTick are processed before IO callbacks whereas callbacks passed to setImmediate are processed after any that are already pending.

Replace process.nextTick(compute); with setImmediate(compute); .

Moving the CPU work to a child process or worker is also possible. But I won't describe that as my main point was to explain how:

function compute() {
  ...
  console.log("good");
  process.nextTick(compute);
}

would block the HTTP server from handling requests ignoring the while loop which has its own problem.

See setImmediate vs. nextTick for more.