Node.js reliability for large application

Question

I am new to Node.js and am currently questioning its reliability.

Based on what I've seen so far, there seems to be a major flaw: any uncaught error/exceptions crashes the server. Sure, you can try to bullet-proof your code or put try/catch in key areas, but there will almost always be bugs that slip through the crack. And it seems dangerous if one problematic request could affect all other requests. There are 2 workarounds that I found:

1. Use daemon or module like forever to automatically restart the server when it crashes. The thing I don't like about this is that the server is still down for a second or two (for a large site, that could be hundreds (of thousands?) of request).

2. Catch uncaught exceptions using process.on('uncaughtException'). The problem with this approach (as far as I know) is that there is no way to get a reference to the request that causes the exception. So that particular request is left hanging (user sees loading indicator until timeout). But at least in this case, other non-problematic requests can still be handled.

Can any Node.js veteran pitch in?

Answer 1

For automatic restarts and load-balancing, I'd suggest you check out Learnboost's up balancer.

It allows you to reload a worker behind the load-balancer without dropping any requests. It stops directing new requests towards the worker, but for existing requests that are already being served, it provides workerTimeout grace period to wait for requests to finish before truly shutting down the process.

You might adapt this strategy to be also triggered by the uncaughtException event.