Can't kill a specific worker in Node.js cluster using Koa framework

We are using a c++ dll from Node.js server using FFI node module. The C++ dll exposes many functions, that the Node.js server is using.

The C++ dll has a characteristic of getting stuck, in some special scenario. And as yet, we do not have a mechanism to heal this up from within the C++ dll. Due to this, the forthcoming requests go un-addressed, because the dll is single-threaded and can take only one request at a time.

The reason we had to use the cluster-worker topology because, we wanted to control the dll from outside.

We have created a fixed number of forks/workers and they are in a pool. For every incoming request, we are assigning the request to a new worker and using the worker with the dll. Whenever the worker is seen taking more than a "healthy" amount of time, we wish to kill it.

We are facing a specific problem, where we are unable to kill a worker, in case the worker is stuck with the c++ dll not responding. This is needed, because of un-handled cases in the c++ dll.

We referred the code for cluster module of Node.js -https://nodejs.org/api/cluster.html#cluster_worker_process

Here are our code snippets -

server_fork.js

var chalk = require( "chalk" ); var cluster = require( "cluster" ); var os = require( "os" );

if ( cluster.isMaster ) { console.log( chalk.red( "[Cluster]" ), "Master process is now running.", process.pid );

for ( var i = 0, coreCount = 2; i < coreCount ; i++ ) {
    var worker = cluster.fork();
}

function messageHandler(msg) {
    console.log('messageHandler')
    if (msg.cmd && msg.cmd === 'notifyRequest') {
      numReqs += 1;
    }
  }

cluster.on(
    "exit",
    function handleExit( worker, code, signal ) {

        console.log( chalk.yellow( "[Cluster]" ), "Worker has died.", worker.process.pid );
        console.log( chalk.yellow( "[Cluster]" ), "Death was suicide:", worker.exitedAfterDisconnect );

            var worker = cluster.fork();
            console.log('new thread');
    }
);

cluster.on(
    "message",
    function handleExit( worker, code, signal ) {
        let timeout
        if (code.cmd == 'started'){
            worker.toBeKilled = true
            timeout = setTimeout(() => {
                if(worker.toBeKilled){
                    try{
                    console.log('inside worker to be killed')
                    // worker.disconnect()
                    worker.kill()
                    //process.exit(0)
                    // process.exit()
                    }catch(err){
                        console.log('err',err)
                    }

                }
              }, 2000);
        } else {
            worker.toBeKilled = false
        }

    }
);
function messageHandler(msg) {
    if (msg.cmd && msg.cmd === 'notifyRequest') {
        console.log('notifyRequest');
    }
  }

} else {

require( "./server" );
console.log( chalk.red( "[Worker]" ), "Worker has started.", process.pid );

} server.js

const Koa = require('koa'); var mount = require('koa-mount'); var serve = require('koa-static'); var bodyParser = require('koa-bodyparser'); var koaBody = require('koa-body'); var api = require('./../src/modules/bvp/router.js'); var jwt = require('koa-jwt');

const app = new Koa(); var hbs = require('koa-hbs'); const convert = require('koa-convert'); const co = require('co');

app.use(convert(hbs.middleware({ viewPath: __dirname + '/../src/views', })));

app.use(async (ctx, next) => { const render = ctx.render; ctx.render = async function _convertedRender () { return co.call(ctx, render.apply(ctx, arguments)); } await next(); });

if (!process.env.NODE_ENV || process.env.NODE_ENV === 'devlopment') { app.use(mount('/swagger', serve(${process.cwd()}/../swagger))) }

app.use(koaBody()); app.use(bodyParser()); app.use(api.routes());

app.listen(3000, function() { console.log('server started on port 3000'); });

module.exports = app; controller.js

err { Error: kill ESRCH at exports._errnoException (util.js:1050:11) at process.kill (internal/process.js:188:13) at Timeout.setTimeout [as _onTimeout] (C:\Data\projects\BVP_backend - Copy\bin\server_fork.js:65:33) at ontimeout (timers.js:386:14) at tryOnTimeout (timers.js:250:5) at Timer.listOnTimeout (timers.js:214:5) code: 'ESRCH', errno: 'ESRCH', syscall: 'kill' } We have already referred a similar problem in Express framework - link https://stackoverflow.com/questions/42106004/cant-kill-a-specific-worker-in-node-js-cluster

koajs / koa

Can't kill a specific worker in Node.js cluster using Koa framework #1235