timers: eventloop is blocked when there are two or more callback duration is larger than interval

[zhangzifa]

• Version: 6.x 7.x 8.x master:
• Platform: n/a:
• Module: timers:

When there are at least two timer set by setInterval, whose callback execution time are longer than interval, the eventloop will be blocked, meanwhile the 4.x is not. You may take the following code to have a test.

@Fishrock123 It seems the timers module refactoring brings this.

const http = require('http');

const sleep = function(ms) {
  const st = new Date().getTime();
  while (new Date().getTime() < st + ms);
};

const t1 = setInterval(function(){
  sleep(100);
}, 50)

const t2 = setInterval(function(){
  sleep(60);
}, 50);

http.createServer(function(req, res) {
  res.end('hello ' + new Date());
}).listen(8888);

[zhangzifa]

@Fishrock123 Could you help review timers: fix eventloop block #15072

I know there should be an extra test for this issue. However, I will be ooo in the following 5/6 days. I will add it when I am back.

[bnoordhuis]

@Fishrock123 Ping, since you self-assigned.