olympum

Update: Jason Hoffman (Chief Scientist, Founder of Joyent) has written a very good response to this post. Obviously I owe him some responses, which is on a separate post.

If you have not watched Douglas Crockford’s video lecture on server-side Javascript, I recommend you do that first before reading further into this post.

I have been saying for a while that server-side Javascript matters. We, at Yahoo!, see a bright future in server-side Javascript and are making a big investment in it. But if you follow me on twitter, you’ll know that I am also looking into ensuring high-availability of server-side Javascript-based services on production. Which really comes down to something like: to V8 or not to V8.

NodeJS is currently tightly coupled to Google’s V8 engine. V8 was not designed as a server-side engine, but as a browser-based engine. Furthermore, V8 was designed squarely to run in Chrome’s multi-process model. As much as I think V8 is a brilliant piece of engineering, it’s software that was not designed to run on a server.

More to the point, it’s really up to Google to work with the community to make V8 work on the server-side. Sometimes Google is responsive, but sometimes it might not. It varies as it depends how fixing a bug or applying a patch may align with Google’s product roadmap and plans. I don’t know Google’s plans, and I suspect most NodeJS committers don’t know either.

Maybe for some folks this might not seem like a big problem. And probably, if you are running a site with a few thousand daily page views, it might actually not be a big deal. But to Yahoo!, and to others, it’s a big deal and we believe this is fundamental to the success of the NodeJS project.

Writing a Javascript runtime that does not fail is hard. Even the really smart V8 folks have explicitly designed V8 for failures to happen and safeguard the browser. In a browser, a JS engine failure is an inconvenience to the user: damn, you lost a tab. In a thread-per-request blocking I/O server design it’s also not a big deal, you lose one in-flight request. But in an event-driven web server, it’s a major flaw, you lose thousands of in-flight requests you have already accepted.

For NodeJS to scale to billions of page views like Yahoo!’s, we need to make sure the Javascript engine / VM behind Node is rock-solid for server-side loads, i.e. it fails extremely rarely.

Google may invest on supporting V8 on the server-side, just like the Mozilla folks do. Or somebody else might invest and ensure V8 is rock-solid on the server and Google may merge the patches nicely. Or maybe not, and the community may need to fork V8. Or something else … Nobody really knows.

Either way, it’s time for the NodeJS community to realise there is a roadblock and discuss it openly.