BTHREADS_BACKEND=child_process SIGINT handling

For my specific use case in a node app, I’d like jobs created as processes (lots of IO and long running). Experimenting with the examples, I’ve come up with the parent / child code as per below. The problem is I cannot get the exception handling to work properly without a “sleep” after it calls bree.stop(). With it, it works as expected. My naive understanding is that signal handlers should not be async in nature. Is there a better way? BTW, same problem exists if I use Graceful.

Main "dispatch" app 

const path = require('path');
 
// optional
const ms = require('ms');
const dayjs = require('dayjs');
const Graceful = require('@ladjs/graceful');
const Cabin = require('cabin');
const later = require('@breejs/later');
 
// required
const Bree = require('bree');
const sleep = require('util').promisify(setTimeout);

process.on('SIGINT',  () => {
    myExit('SIGINT');
});
process.on('SIGQUIT',  () => {
    myExit('SIGQUIT');
});
process.on('SIGTERM',  () => {
    myExit('SIGTERM');
});
async function myExit(name) {
    console.log(`\mBREE Parent Ending ${name}`);
    bree.stop();
    //removing sleep here now does not allow child to close properly (at least no logging is seen but process is closed)
    await sleep(500);
    process.exit(0);
}

console.log(`BREE starting with PID:${process.pid}`);

//
// NOTE: see the "Instance Options" section below in this README
// for the complete list of options and their defaults
//
const bree = new Bree({
  //
  // NOTE: by default the `logger` is set to `console`
  // however we recommend you to use CabinJS as it
  // will automatically add application and worker metadata
  // to your log output, and also masks sensitive data for you
  // <https://cabinjs.com>
  //
  // logger: new Cabin(),
 
  //
  // NOTE: instead of passing this Array as an option
  // you can create a `./jobs/index.js` file, exporting
  // this exact same array as `module.exports = [ ... ]`
  // doing so will allow you to keep your job configuration and the jobs
  // themselves all in the same folder and very organized
  //
  // See the "Job Options" section below in this README
  // for the complete list of job options and configurations
  //
  jobs: [
    // runs `./jobs/foo.js` on start
    // 'job-async',
//    'job-async',

    //'job-compute'
    
    // runs `./jobs/worker-5.js` on after 10 minutes have elapsed
    {   
      name: 'job-async-copy',
      interval: 5000,//later.parse.text('every 5 seconds'),
      worker: {
          workerData: { name: 'joe' }
      }

    },
    
  ]
});
 
// handle graceful reloads, pm2 support, and events like SIGHUP, SIGINT, etc.
// const graceful = new Graceful({ brees: [bree] });
// graceful.listen();
 
// start all jobs (this is the equivalent of reloading a crontab):
bree.start();

//bree.stop('job-async');

/*
// start only a specific job:
bree.start('foo');
 
// stop all jobs
bree.stop();
 
// stop only a specific job:
bree.stop('beep');
 
// run all jobs (this does not abide by timeout/interval/cron and spawns workers immediately)
bree.run();
 
// run a specific job (...)
bree.run('beep');
 
// add a job array after initialization:
bree.add(['boop']);
// this must then be started using one of the above methods
 
// add a job after initialization:
bree.add('boop');
// this must then be started using one of the above methods
 
// remove a job after initialization:
bree.remove('boop');
*/

bree.on('worker deleted', (name) => {
    console.log('worker deleted', name);
    // if (name === 'job-async' && !signal) 
    //     bree.run(name);
  });

bree.on('worker created', (name) => {
    console.log(`new worker ${name}`);
});  

Job

const threads = require('bthreads');
const sleep = require('util').promisify(setTimeout);

let signal = false;

process.on('SIGINT',  () => {
    myExit('SIGINT');
});
process.on('SIGQUIT',  () => {
    myExit('SIGQUIT');
});
process.on('SIGTERM',  () => {
    myExit('SIGTERM');
});

function myExit(name) {
    console.log(`ASYNC received ${name}`);
    signal = true;

    // if (threads.parentPort) {
    //     threads.parentPort.postMessage('cancel');
    //     console.log(`Cancel sent`);
    // } else 
    //     console.log(`Exiting...`);
}
if (!threads.isMainThread) {
    threads.parentPort.on('message', async (message) => {
        console.log(`Received message from parent [${message}]`);
    //    await sleep(300);
        if (message === 'cancel') {
            signal = true;
        }   
    });
}

if (threads.isMainThread) {
    console.log(`ASYNC on main threads`);
    
} else {
    console.log(`ASYNC on worker thread`);

}

// if (threads.parentPort) {
//     console.log(`Adding .... event receiver`);
//     threads.parentPort.once('message', async (message) => {
//     });
// }


let a = 1;
let name = 'll'; //threads.hasOwnProperty('workerData.name')  ? "UNKNOWN" : threads.workerData.name
console.log(`async-COPY starting with PID:${process.pid} and name ${name}`);
async function x() {
    for (;;) {
        a++;
        await sleep(300);
        console.log(`COPY loop ${a}`);
        // if (a==5) 
        //     threads.parentPort.postMessage('error');
        if (a>10 || signal) {
            // if (threads.parentPort) {
            //     threads.parentPort.postMessage('COPY exit');
            // }
            if (signal) {
                console.log(`COPY Exiting due to signal...`);
                if (!threads.isMainThread) {
                    console.log(`Sending to Parent...`);
                    threads.parentPort.postMessage('cancelled');
                }
            }
            process.exit(0);
        }
    }
}

x();

[niftylettuce]

v3.4.0 released to npm, thank you @naz for the fix and quick PR, truly appreciate your contribution, means a lot.

https://github.com/breejs/bree/releases/tag/v3.4.0

[niftylettuce]

I don’t have time to look at this yet, perhaps @shadowgate15 can