Question

I’m using NodeJS to run a socket server (using socket.io). When a client connects, I want am opening and running a module which does a bunch of stuff. Even though I am careful to try and catch as much as possible, when this module throws an error, it obviously takes down the entire socket server with it.

Is there a way I can separate the two so if the connected clients module script fails, it doesn’t necessarily take down the entire server?

I’m assuming this is what child process is for, but the documentation doesn’t mention starting other node instances.

I’d obviously need to kill the process if the client disconnected too.

Answer 1

I’m assuming these modules you’re talking about are JS code. If so, you might want to try the vm module. This lets you run code in a separate context, and also gives you the ability to do a try / catch around execution of the specific code.

You can run node as a separate process and watch the data go by using spawn, then watch the stderr/stdout/exit events to track any progress. Then kill can be used to kill the process if the client disconnects. You’re going to have to map clients and spawned processes though so their disconnect event will trigger the process close properly.

Finally the uncaughtException event can be used as a “catch-all” for any missed exceptions, making it so that the server doesn’t get completely killed (signals are a bit of an exception of course).