docs/api/utility-process.md
utilityProcess creates a child process with
Node.js and Message ports enabled. It provides the equivalent of child_process.fork API from Node.js
but instead uses Services API from Chromium to launch the child process.
Process: Main
utilityProcess.fork(modulePath[, args][, options])modulePath string - Path to the script that should run as entrypoint in the child process.args string[] (optional) - List of string arguments that will be available as process.argv
in the child process.options Object (optional)
env Object (optional) - Environment key-value pairs. Default is process.env.execArgv string[] (optional) - List of string arguments passed to the executable.cwd string (optional) - Current working directory of the child process.stdio (string[] | string) (optional) - Allows configuring the mode for stdout and stderr
of the child process. Default is inherit.
String value can be one of pipe, ignore, inherit, for more details on these values you can refer to
stdio documentation from Node.js. Currently this option only supports configuring stdout and
stderr to either pipe, inherit or ignore. Configuring stdin to any property other than ignore is not supported and will result in an error.
For example, the supported values will be processed as following:
pipe: equivalent to ['ignore', 'pipe', 'pipe']ignore: equivalent to ['ignore', 'ignore', 'ignore']inherit: equivalent to ['ignore', 'inherit', 'inherit'] (the default)serviceName string (optional) - Name of the process that will appear in name property of
ProcessMetric returned by app.getAppMetrics
and child-process-gone event of app.
Default is Node Utility Process.allowLoadingUnsignedLibraries boolean (optional) macOS - With this flag, the utility process will be
launched via the Electron Helper (Plugin).app helper executable on macOS, which can be
codesigned with com.apple.security.cs.disable-library-validation and
com.apple.security.cs.allow-unsigned-executable-memory entitlements. This will allow the utility process
to load unsigned libraries. Unless you specifically need this capability, it is best to leave this disabled.
Default is false.disclaim boolean (optional) macOS - With this flag, the utility process will disclaim
responsibility for the child process. This causes the operating system to consider the child
process as a separate entity for purposes of security policies like Transparency, Consent, and
Control (TCC). When responsibility is disclaimed, the parent process will not be attributed
for any TCC requests initiated by the child process. This is useful when launching processes
that run third-party or otherwise untrusted code. Default is false.respondToAuthRequestsFromMainProcess boolean (optional) - With this flag, all HTTP 401 and 407 network
requests created via the net module will allow responding to them via the
app#login event in the main process instead of the default
login event on the ClientRequest object. Default is
false.Returns UtilityProcess
[!NOTE]
utilityProcess.forkcan only be called after thereadyevent has been emitted onApp.
Instances of the
UtilityProcessrepresent the Chromium spawned child process with Node.js integration.
UtilityProcess is an EventEmitter.
child.postMessage(message, [transfer])message anytransfer MessagePortMain[] (optional)Send a message to the child process, optionally transferring ownership of
zero or more MessagePortMain objects.
For example:
// Main process
const { port1, port2 } = new MessageChannelMain()
const child = utilityProcess.fork(path.join(__dirname, 'test.js'))
child.postMessage({ message: 'hello' }, [port1])
// Child process
process.parentPort.once('message', (e) => {
const [port] = e.ports
// ...
})
child.kill()Returns boolean
Terminates the process gracefully. On POSIX, it uses SIGTERM but will ensure the process is reaped on exit. This function returns true if the kill is successful, and false otherwise.
child.pidA Integer | undefined representing the process identifier (PID) of the child process.
Until the child process has spawned successfully, the value is undefined. When
the child process exits, then the value is undefined after the exit event is emitted.
const child = utilityProcess.fork(path.join(__dirname, 'test.js'))
console.log(child.pid) // undefined
child.on('spawn', () => {
console.log(child.pid) // Integer
})
child.on('exit', () => {
console.log(child.pid) // undefined
})
[!NOTE] You can use the
pidto determine if the process is currently running.
child.stdoutA NodeJS.ReadableStream | null that represents the child process's stdout.
If the child was spawned with options.stdio[1] set to anything other than 'pipe', then this will be null.
When the child process exits, then the value is null after the exit event is emitted.
// Main process
const { port1, port2 } = new MessageChannelMain()
const child = utilityProcess.fork(path.join(__dirname, 'test.js'))
child.stdout.on('data', (data) => {
console.log(`Received chunk ${data}`)
})
child.stderrA NodeJS.ReadableStream | null that represents the child process's stderr.
If the child was spawned with options.stdio[2] set to anything other than 'pipe', then this will be null.
When the child process exits, then the value is null after the exit event is emitted.
Emitted once the child process has spawned successfully.
Returns:
type string - Type of error. One of the following values:
FatalErrorlocation string - Source location from where the error originated.report string - Node.js diagnostic report.Emitted when the child process needs to terminate due to non continuable error from V8.
No matter if you listen to the error event, the exit event will be emitted after the
child process terminates.
Returns:
code number - Contains the exit code for
the process obtained from waitpid on POSIX, or GetExitCodeProcess on Windows.Emitted after the child process ends.
Returns:
message anyEmitted when the child process sends a message using process.parentPort.postMessage().