README
fork-worker
Makes it easier to fork off a separate Node.js worker with a heavy job or some code you don't trust the stability of (maybe a high risk of crashing the whole node process, like a native module). fork-worker lets you run a js file outside the calling process (uses child_process.fork internally). It will make sure that the process is killed when done, and returns a promise for ease of use.
Install
npm install fork-worker
Usage
Signature
forkWorker(modulePath, opts) -> Promise|ChildProcess
modulePath (required) - Passed to child_process.fork
opts: { message, timeout, args, options } (optional) - As follows:
message (optional) - Message to be sent to process.on('message', (message) => { ... }) in the worker. Must be serializable. If not specified, the child process will get a null.
timeout (optional) - If specified and the process has not called process.send or failed within this time, the process will be killed and the promise will be rejected. Default: undefined
args (optional) - Passed on to child_process.fork(modulePath, args, options)
options (optional) - Passed on to child_process.fork(modulePath, args, options)
Return value
A Promise that will be resolved when the worker posts a message (resolved with the message.) The promise will be rejected if the process exits without sending a message, times out, crashes, or reports an error. The returned promise is also a ChildProcess class (from child_process.fork()).
Example
worker.js
const riskyOperation = require('some-heavy-or-unstable-module');
process.on('message', async (inData) => {
try {
const data = await riskyOperation(inData)
process.send({ data })
} catch (err) {
// Important that we catch async errors because unhandled promise rejections will not terminate Node.js.
console.log('worker error', err)
process.send({ error: 'Something went wrong' })
}
});
index.js
const forkWorker = require('fork-worker');
async function safelyRunRiskyOperation(inData) {
try {
const response = await forkWorker('./worker.js', { message: inData, timeout: 10000 });
if (response.error) throw new Error('Worker reported error')
return response.data;
} catch (err) {
console.log('Worker error', err)
}
}