Is there any limit to setTimeout?

Question

Specifically talking about (server side) V8, and assuming I'm not concerned about accuracy because I can detect and compensate for it, could I literally set up thousands of relatively simple timeouts several seconds apart from each other using setTimeout without facing any other limit other than RAM? Is there any catch I should be aware of if I were to use a system where there may be thousands of scheduled timeouts at any given time?

For the record I've read John's Resig excellent article on How Javascript Timers work so no need to point out anything that's already covered there :) I'm aware node.js is single threaded, timers can block other timers if they take too long, etc.

PS: I'm strictly trying to understand how viable is what I describe, no need to point out "there's surely a better way to do what you intend to do!".

there's guaranteed a better way to do what you intend to do! — jAndy, Aug 28 '12 at 22:58
Setting up a few million timeouts is just a `for` loop away. Try it and tell us instead. ;) — Jon, Aug 28 '12 at 23:40
@Jon I tried this because I was also wondering and I believe it was not that expensive... — Alfred, Aug 29 '12 at 05:01

score 15 · Accepted Answer · answered Aug 29 '12 at 08:34

The only real world limit you may come up against is the amount of memory available to node. Use the following code to test. I successfully ran the example below using oneMillion and int32Max. When using int64Max, I received the following error from node. I'm using 64bit windows with 4gb of RAM.

FATAL ERROR: CALL_AND_RETRY_2 Allocation failed - process out of memory

Node code to test:

var util = require('util');
var int64Max = 9007199254740992; 
var int32Max = 2147483647;
var oneMillion = 1000000;
var tenThousand = 10000;
var counter = 0;

//Exchange the limiter with one of the above vars to test.
for (var i = 0; i < oneMillion; i++){   
     setTimeout(log, 1);
     //Required as the timeout/callback method will not be called until the loop ends due 
     //to node/js being single threaded.
     util.log('loop:' + i);
}

function log(){
     util.log('callback: ' + counter++);
}

Javascript numbers have 53 bits of mantissa, so once it reaches around 2^53, the increment no longer works, it rounds off to the same number without causing any change. Doubt it? Try `Math.pow(2,53)` and `Math.pow(2,53)+1` in a debugger console. Why is `int64Max` mentioned at all? — doug65536, Oct 19 '15 at 22:54
I haven't a `process out of memory`, but when I do a timeout higher than `2147483647`, the callback function is directly launch ! I'm running it inside a docker container btw — Mcsky, May 24 '18 at 08:51

score 2 · Answer 2 · answered Aug 28 '12 at 23:02

2

I don't know how node operates, but if you create MAXINT+1 timers without letting them run, you risk an integer overflow.

answered Aug 28 '12 at 23:02

Jeremy J Starcher

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score 1 · Answer 3 · answered Aug 31 '23 at 13:31

1

I have come to find, through my own experience, that a single setTimeout has a maximum delay of 2500000000 milliseconds (about 29 days). Anything beyond that delay, and it actions the code/function straight away - as if the delay were 0 milliseconds.

answered Aug 31 '23 at 13:31

ckhatton

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Is there any limit to setTimeout?

3 Answers3

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