tapppi / async-exit-hook Goto Github PK

run nodejs app as:
pm2 start app.js
it run successfully. Then I tried to stop app:
pm2 stop id

But it can not trigger exitHook()

Hello,

it looks like you can bind to both. Is there any particoular reason?

Also, would you expose the exit function so that one can eventually calll it manually?

Let me illustrate the problem with the following code:

const cluster = require("cluster");
const exitHook = require("async-exit-hook");

function addHook(delay) {
    exitHook(cb => {
        console.log("Start " + delay);
        setTimeout(() => {
            console.log("Finish " + delay);
            cb()
        }, delay);
    });
}

if (cluster.isMaster) {
    cluster.fork();
} else {
    addHook(0);
    addHook(1);
    addHook(10);
    addHook(100);
}

If I start this script and kill it with ctrl+c, then I get:

$ node exitHook.js
^C
$ Start 0
Start 1
Start 10
Start 100
Finish 0
Finish 1

As you can see, only the very fast exit hooks are executed. This problem only happens in workers. Is this a known issue?

Versions:

• Node: v10.16.3 and v12.8.0
• Async exit hook: 2.0.1
• Operating system: Ubuntu 18.04.1 LTS

The runHook method has no error handling:

if (err) {
  // Pass error, calling uncaught exception handlers
  return hook(err, stepTowardExit);
}
return hook(stepTowardExit);

If a hook throws, then the exit procedure stops and exit is never actually achieved. (I found this by hitting #9 which threw in an exit routine.)

This could be fixed by wrapping in a try/catch and calling stepTowardsExit on error.

This would be useful to control the order of exit hooks execution where required. Use case: if I am using it for shutting down dependant processes gracefully, I am probably expecting to have logging being shut down as last.

Please, could you provide an example of how use NodeMailer to send an email on Node exit? I can't figure it out how to integrate callback with nodemailer's promise. Thanks.

callback is always called
https://github.com/Tapppi/async-exit-hook/blame/80e692c88e62a88cf5750460ff02c28298e5b09b/readme.md#L60

callback is not always provided

should be

exitHook(callback => {
    setTimeout(() => {
        console.log('exiting 3');
        if(callback) callback();
    }, 1000);
});

When calling exit hook, like so:

exitHook(cb => { /* do something on exit */ })

cb may not be a function depending on how the async-exit-hook routine is entered. If it's entered with an uncaught error, then it's called with 2 params and the second is the callback.

if (exit && hook.length > syncArgCount) {
  // Hook is async, expects a finish callback
  waitingFor++;

  if (err) {
    // Pass error, calling uncaught exception handlers
   return hook(err, stepTowardExit); // call called with 2 params
  }
  return hook(stepTowardExit); // <-- called with 1 param
}

This would be easy to fix by simply changing the second to:

return hook(null, stepTowardExit);

Because this is a breaking change to the API, it probably warrants a major version upgrade.