Question 112176 in Ubuntu Question posted in
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Ubuntu – PM2 is catching errors before they reach 'uncaught Exception' in Node.js

Hey Guys,
I am running a discordbot with Discord.js in Node.js. My goal is to run it via pm2 on a Linux Ubuntu Server.

I want to build a cleanup process before exiting the program on uncaught Exception.

However when I throw a sample error and run it via pm2 uncaught Exception is not reached, pm2 is just logging the error and continue running the script.
When running it directly with Node.js, without pm2 everything works as expected.

Here is my code:

process.on('uncaughtException', async (err, origin) => {
    console.log('test')
    // await Cleanup();
    process.exit(1);
});

Here the console output running it with pm2:

Error: Test error
at Object.execute (script xxxx)
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
at async xxx

As you can see pm2 is kind of preventing the Test error to reach uncaughtException. Pm2 is not restarting the script, and is not logging ‘test’

I also tried catching the error via SIGINT or SIGTERM but none of these are working.

Is there an option in pm2 to disable this behavior?

Thanks for any help!

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2

Answers


  1. Chosen as BEST ANSWER
    0

    The function in which the error is thrown is async. That led me to the docs of the unhandledRejection event.

    In addition to uncaughtException I added unhandledRejection:

    process.on('uncaughtException', async (err, origin) => {
  await Cleanup(...); //my own cleanup
  process.exit(0);
});

process.on('unhandledRejection', async (reason, promise) => {
  await Cleanup(...); //my own cleanup
  process.exit(0);
});

    Now pm2 is restarting after a cleanup whenever an uncaught Error/Exception is thrown.


  2. 0

    PM2 automatically restart applications when they crashed or terminate.

    As i remember, you can not disable this: https://pm2.keymetrics.io/docs/usage/restart-strategies/

    UPDATE

    Normally process.exit(0); will restart the pm2 process.

    You also have a workaround to force restart from within your app.
    You need to start your app with the --watch parameter:

    pm2 start app.js --watch

    Thus, you just need to write/modify/delete a temp file in a directory inside your application directory. When pm2 detect new file it will restart your app. It’s not a clean solution, but this work.

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