NestJS 中的集群

Question

Why lib the cluster dont work in NestJS?
MY VERSION NODE: 18.1.0

IMPLEMENTATION:

import cluster from 'cluster';
import os from 'os';

export function inCluster(callback: Function, workers? : number) {
    if(cluster.isPrimary) {
        process.on('SIGINT', function () {
            for(let id in cluster.workers) {
                cluster.workers[id].kill();
            }
            process.exit(0);
        });

        const cpus = os.cpus().length;
        if(workers == null || workers > cpus) workers = cpus;

        for(let i = 0; i < workers; i++) cluster.fork(); 
        
        cluster.on('online', function (worker) {
            console.log(`Worker ${worker.process.pid} is online`)
        }); 

        cluster.on('exit', (worker, code, signal) => {
            console.log(`worker ${worker.process.pid} died. Restarting`); 
            cluster.fork(); 
        });
    }

    callback();
}

ERROR:

teste_cluster/src/cluster.ts:5
    if(cluster.isPrimary) {
            ^
TypeError: Cannot read properties of undefined (reading 'isPrimary')
    at inCluster (/home/simoes/repositories/teste_cluster/src/cluster.ts:5:13)
    at Object.<anonymous> (/home/simoes/repositories/teste_cluster/src/main.ts:10:10)
    at Module._compile (node:internal/modules/cjs/loader:1105:14)
    at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
    at Module.load (node:internal/modules/cjs/loader:981:32)
    at Function.Module._load (node:internal/modules/cjs/loader:827:12)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:77:12)
    at node:internal/main/run_main_module:17:47

I trieng change of the import for this:

import cluster from 'node:cluster';
import os from 'node:os';

as the nodejs documentation demonstrates:
https://nodejs.org/dist/latest-v18.x/docs/api/cluster.html

Answer 1

You should try type: const cluster = require('cluster'); instead of import cluster from 'cluster'; . In my case this solved the issue. What is more you should consider type cluster.schedulingPolicy = cluster.SCHED_RR; if you running your app on windows. More info at node-js-typescript-power-of-many-processes-cluster "Scheduling policy" section.