MakeCallback is very slow

[ronag]

Calling into JS from CPP is very slow. Is this due to async hooks? Could we disable that with a global option if the user doesn't need async hooks?

[joyeecheung]

See past discussions nodejs/node#10101 - I think the conclusion was that it wasn't that slow, but that was measured 6 years ago and before V8 rolled out several architectural redesigns. We have also deprecated domains for a long time. Maybe the situations have changed now. Would be good to have some new measurements to see if it is worth a shot making it some kind of optional thing.

[anonrig]

Could we disable that with a global option if the user doesn't need async hooks?

Can you explain this in detail? I'm trying to understand the current implementation, and a quick explanation could/would save a lot of time :)

[ronag]

Could we disable that with a global option if the user doesn't need async hooks?

Can you explain this in detail? I'm trying to understand the current implementation, and a quick explanation could/would save a lot of time :)

I don't know much about the details. Async hooks are used to propagate async context. It has a constant overhead even if you don't use it.

[mcollina]

async_hooks have a tiny overhead if disabled and a significant overhead if enabled.

[ronag]

async_hooks have a tiny overhead if disabled and a significant overhead if enabled.

Is it possible to disable it?

[mcollina]

Not really. That's described in the linked issue. Maybe a compile-time flag could do it but we are talking ns of difference.

[abenhamdine]

see also previous related work in
nodejs/node#41331
nodejs/node#41279
some big picture datapoints here, related to uWebSockets module : uNetworking/uWebSockets.js#341

[benjamingr]

Interesting stuff (though bad manners) at uNetworking/uWebSockets.js#904 namely that experiment (that does break async_hooks but also improves performance)