How to end cluster's worker process gracefully?

[avz]

How i can cause exit of worker process (end worker's event loop) without calling process.exit()?

var cluster = require('cluster');

if(cluster.isMaster) {
    process.stdout.write('Starting worker ... ')

    cluster.fork();

    cluster.on('death', function(worker) {
        console.log('worker ' + worker.pid + ' died');
    });
} else {
    process.stdout.write('done\n')
    process.stdout.write('Now worker must gracefully die\n')
}

Result

arepo@home [/tmp]# node a.js
Starting worker ... done
Now worker must gracefully die
<...nothing happens...>
^Czsh: exit 1     node a.js

Expected result:

arepo@home [/tmp]# node a.js
Starting worker ... done
Now worker must gracefully die
worker 9992 died
arepo@home [/tmp]#

[bnoordhuis]

Call process.exit() in the worker. The worker has an open communication channel with the master that's keeping the event loop alive.

[avz]

Well, but we need to syncronize end of all async actions in program because process.exit() may break it. We must to use something like semaphore to avoid it

var cluster = require('cluster');
var http = require('http');

if (cluster.isMaster) {
    cluster.fork();

    cluster.on('death', function(worker) {
        console.log('worker ' + worker.pid + ' died');
    });
} else {
    var semaphore = new Semaphore(1)
    semaphore.on('zero', function() {
        process.exit()
    })

    var server = http.Server(function(req, res) {
        /* ... */

        semaphore.inc()
        try {
            smthAsyncAction(function() {
                semaphore.dec()
            })
        } catch(e) {
            semaphore.dec()
            throw e
        }

        /* ... */
    }).listen(8000);

    server.on('end', function() {
        semaphore.dec()
    })
}

but our code would be much easier if there was a method like cluster.ipc.close():

var cluster = require('cluster');
var http = require('http');

if (cluster.isMaster) {
    cluster.fork();

    cluster.on('death', function(worker) {
        console.log('worker ' + worker.pid + ' died');
    });
} else {
    var server = http.Server(function(req, res) {
        /* ... */

        smthAsyncAction(function() {
            /* ... */
        })

        /* ... */
    }).listen(8000);

    server.on('end', function() {
        cluster.ipc.close()
    })
}

[bnoordhuis]

@ry I suppose @avz has a point. Maybe add something like a cluster.destroySoon() that unrefs the worker's IPC channel?

[AndreasMadsen]

I'm working on this in #2038 but I don't know how to close the IPC between master and worker. Can someone give me a hint?

[AndreasMadsen]

It just got an inspiration worker.process._channel.close(), but I'm not sure it works since there are no IPC when running the .disconnect() method.

[ry]

We can't take API changes in v0.6, sorry. worker.process._channel.close() is the work around for now, yes.