Any tips for improving performance of `vm.run()`?

[theinterned]

Any tips for improving performance of `vm.run()`?

[XmiliaH]

VM2 does not allow for es modules, so there is no dynamic import.

[XmiliaH]

There is currently no way to improve this as require files are not cached. You can try the following hack which gave me a 10% speed boost.

const options = {
	require: { external: true, root: './'}
};
const script = new VMScript(`module.exports = require('uuid');`);
const { packageCache, scriptCache } = new NodeVM(options)._resolver ?? {};

function render(args) {
	const vm = new NodeVM(options);
	try {
		Object.assign(vm._resolver ?? {}, { packageCache, scriptCache });
	} catch { /* This is currently a hack! */ }
	const handler = vm.run(script);
	return handler(args);
}

This shares the internal package and script caches for require between the instances. Getting the performance better than this will likely not be possible.

[XmiliaH]

They will not leak any data between vms. It only caches the compiled VMScripts for modules so that hopefully require will be a bit faster.

[theinterned]

As a follow up: @XmiliaH , your optimization has been a HUGE perf win for us. Using pretty much exactly your code, I am able to get the time to create a fresh render context from ~1.5s all the way down to ~100ms! 🚀

I think this makes sense as the script we're requiring in our VM is in fact an entire webpack bundle of react code, so avoiding re-linking everything is a major win.

Thank you so much this is awesome!

One question I have about this: this _resolver definitely seems to be a private API: it's not exposed on the NodeVM type. Would you consider changing this and making a public API for this?

[XmiliaH]

Thanks for the feedback. Yes _resolver is a private API. I will look into making a public API for this.

[XmiliaH]

@theinterned Could you take a look at #519 if it would fit your usecase.

[theinterned]

Oh thanks wow 🤩! I will give this a try. Will sharing the packageCache and scriptCache leak any data between vms?

[theinterned]

Oh #519 looks very interesting! I ran out of time to try it out this week, but I'll mess around with it next week for sure. Thanks you! ⭐⭐⭐⭐⭐

[manuelpuyol]

hey @XmiliaH, do you know if the _resolver cache would also impact dynamic imports?