Function is running multiple time as per CPU core(CPU cores = 4 in my case). How can I run function only 1 time?

debugcn Published at Dev

Nishant Khandelwal

In my Node js application due to clustering, the function is executing multiple time. How can I run a function only 1 time? Actually, want to run cron job but due to multiple execution of the function, cron is executing multiple time.

Clustering code: `

var numCPUs = require('os').cpus().length;
if (cluster.isMaster) {
    // Fork workers.
    // console.log('numCPUs--------',numCPUs);
    for (var i = 0; i < numCPUs; i++) {
        cluster.fork();
        console.log(process.pid);
    }
    cluster.on('exit', function (worker, code, signal) {
        // handle server crashes
        console.log('worker ' + worker.process.pid + ' died');
    });
} else {
    console.log(cluster.worker.id);
    const port = process.env.PORT || 8000;
    app.listen(8000);
}
(function test() {
    console.log("THIS is test");
}());


OUTPUT: 4
THIS is test
1
3
THIS is test
THIS is test
2
THIS is test

Samir Aleido

Move the call to test function to master block

var numCPUs = require('os').cpus().length;
if (cluster.isMaster) {
    test(); // calling test function moved to here
    // Fork workers.
    // console.log('numCPUs--------',numCPUs);
    for (var i = 0; i < numCPUs; i++) {
        cluster.fork();
        console.log(process.pid);
    }
    cluster.on('exit', function (worker, code, signal) {
        // handle server crashes
        console.log('worker ' + worker.process.pid + ' died');
    });
} else {
    console.log(cluster.worker.id);
    const port = process.env.PORT || 8000;
    app.listen(8000);
}

// implementing the function only
function test () {
    console.log("THIS is test");
}

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