Need help understanding Node.js CPU consumption

[Sunil Agrawal]

If my entire Node.js program is the following 

setInterval(function() {}, Infinity) 

'top' shows it consumes 15-20% CPU

If I change it to

setInterval(function() {}, 100000)

it drops down to < 1% CPU consumption.

Any insights what's going on?

TIA,

Sunil 

[Ben Noordhuis]

setInterval() in node.js follows what browsers do: intervals >
2,147,483,647 milliseconds are treated as $smallest_timeout intervals
(= 1 ms in node.js.)

In other words, `setInterval(function() {}, Infinity)` is identical to
`setInterval(function() {}, 1)`.

[mscdex]

On Tuesday, July 7, 2015 at 8:54:29 AM UTC-4, Sunil Agrawal wrote:

If my entire Node.js program is the following 

setInterval(function() {}, Infinity) 

'top' shows it consumes 15-20% CPU

What is happening here is that since `Infinity` is larger than the maximum allowed timeout value (2147483647 -- 2^31-1), so it changes the value to 1[1], causing the function to execute on *every* tick of the event loop.

Using a value of 100000 is still smaller than the maximum allowed timeout value, so in that case the function only executes every 100000 milliseconds.

[1] https://github.com/joyent/node/blob/d38e865fce93c00cb128034202fb1e26987efdbc/lib/timers.js#L208-L210

[Alex Giannakakos]

On Tuesday, July 7, 2015 at 6:04:27 PM UTC+3, mscdex wrote:

[1] https://github.com/joyent/node/blob/d38e865fce93c00cb128034202fb1e26987efdbc/lib/timers.js#L208-L210

Minor nitpick: the actual lines for setInterval are in
https://github.com/joyent/node/blob/d38e865fce93c00cb128034202fb1e26987efdbc/lib/timers.js#L255-L257

Great answers!