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cfork

cluster fork and restart easy way.

Easy fork with worker file path
Handle worker restart, even it was exit unexpected.
Auto error log process uncaughtException event

Install

npm install cfork

Usage

ESM and TypeScript

import util from 'node:util';
import { cfork } from 'cfork';

const clusterWorker = cfork({
  exec: '/your/app/worker.js',
  // slaves: ['/your/app/slave.js'],
  // count: require('os').cpus().length,
}).on('fork', worker => {
    console.warn('[%s] [worker:%d] new worker start', Date(), worker.process.pid);
  })
  .on('disconnect', worker => {
    console.warn('[%s] [master:%s] wroker:%s disconnect, exitedAfterDisconnect: %s, state: %s.',
      Date(), process.pid, worker.process.pid, worker.exitedAfterDisconnect, worker.state);
  })
  .on('exit', (worker, code, signal) => {
    const exitCode = worker.process.exitCode;
    const err = new Error(util.format('worker %s died (code: %s, signal: %s, exitedAfterDisconnect: %s, state: %s)',
      worker.process.pid, exitCode, signal, worker.exitedAfterDisconnect, worker.state));
    err.name = 'WorkerDiedError';
    console.error('[%s] [master:%s] wroker exit: %s', Date(), process.pid, err.stack);
  })
  // if you do not listen to this event
  // cfork will output this message to stderr
  .on('unexpectedExit', (worker, code, signal) => {
    // logger what you want
  })
  // emit when reach refork times limit
  .on('reachReforkLimit', () => {
    // do what you want
  });

// if you do not listen to this event
// cfork will listen it and output the error message to stderr
process.on('uncaughtException', err => {
  // do what you want
});

// if you want to dynamically disable refork, you can call the setDisableRefork, priority over the refork parameter
cfork.setDisableRefork(clusterWorker, true);

CommonJS

const { cfork } = require('cfork');

Options

exec : exec file path
slaves : slave process config
args : exec arguments
count : fork worker nums, default is os.cpus().length
refork : refork when worker disconnect or unexpected exit, default is true
limit: limit refork times within the duration, default is 60
duration: default is 60000, one minute (so, the refork times < limit / duration)
autoCoverage: auto fork with istanbul when running_under_istanbul env set, default is false
env: attach some environment variable key-value pairs to the worker / slave process, default to an empty object.
windowsHide: Hide the forked processes console window that would normally be created on Windows systems, default to false.
serialization: Specify the kind of serialization used for sending messages between processes. Possible values are 'json' and 'advanced'. See Advanced serialization for child_process for more details. Default: false.