What is the prefered way of handling uncaughtexception in nodejs application?
FYI, I am having a Express based REST Api nodejs server.
2 Answers
Lot of people do this
process.on('uncaughtException', function (err) {
console.log(err);
});
This is bad. When an uncaught exception is thrown you should consider your application in an unclean state. You can’t reliably continue your program at this point.
Let your application crash, log and restart.
process.on('uncaughtException', function (err) {
console.error((new Date).toUTCString() + ' uncaughtException:', err.message);
console.error(err.stack);
// Send the error log to your email
sendMail(err);
process.exit(1);
})
let your application crash in the event of an uncaught exception and use a tool like forever or upstart to restart it (almost) instantly. You can send an email to be aware of such events.
1 Comment
Константин Ван
The tool to restart them on crashes is called a “process manager.” I’m using PM2 for that.
an exception should do one of two things:
- be caught and handled properly by the program
- cause the program to terminate in catastrophic angry failure
if you have uncaught exception that you are trying to get rid of in your program, you either have a bug to fix, or you need to catch that exception and handle it properly
complicated async code, typically involving a mess of disorganized uncaught promises, is often the cause of many uncaught exception problems -- you need to watch how you return your promise chains very carefully
the only permanent solution is to adopt modern async/await code practices to keep your async code maintainable
1 Comment
Naveen
Yes I agree the code should handle the exception in the first place. but what if, it remained unhandled and bubble uo to the process level?
processevent to allow the process to continue. It's fine to use the event as a chance to retrieve and log additional information before stopping the process, but the process should then still stop (or restart). That information should help you revise other areas of your application's code, so it either doesn't cause the exception or to improve handling of them at the source.