The setInterval function can only be called 66 times per second under Windows.

[FishOrBear]

Version

22.9

Platform

win10 22H2

code:

let i = 0;
setInterval(() =>
{
    i++;
}, 10);

setInterval(() =>
{
    console.log(i);
    i = 0;
}, 1000);

Subsystem

No response

What steps will reproduce the bug?

node

How often does it reproduce? Is there a required condition?

.

What is the expected behavior? Why is that the expected behavior?

100/s

What do you see instead?

66/s

Additional information

No response

[juanarbol]

Hi! I don't think this is an issue.

Is the interval function malfunctioning? If your complaints are about speed; feel free to send a PR so Node.js will achieve your threshold.

[jasnell]

This is not a bug and setInterval() is working as expected. There are reasonable limitations in the way timers work in single threaded event loops and this is just highlighting those. Recommend marking this issue as invalid and closing.

[FishOrBear]

It is much faster on Linux, only slower on Windows

[bnoordhuis]

The explanations above are not incorrect (node is not a real-time system) but the core issue here is the default 64 Hz granularity of timers on Windows, meaning the operating system groups timers in intervals of 1,000/64 = 15.625 ms. A 10 ms timer is prone to getting rounded up to the next interval.

Note how 64 is very close to the 66 calls/sec you're seeing. For comparison, on my Linux machine it hovers around ~97 calls/sec.

One improvement node could maybe make is call timeBeginPeriod(1) to request better timer granularity (like e.g. Chrome does) but that's a precision-vs-efficiency trade-off. Higher precision means higher CPU usage, ceteris paribus.