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 ?

score 4 · Accepted Answer · edited May 23 '17 at 12:14

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.

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

1 Answers1