setupCluster is used to configure the way workers are forked (pretty much the same way the native cluster.setupMaster works). You can call setupCluster more than once, but changes will only be reflected in future forks. The current forking behavior reflects the current settings.
Cerebellum is also environmental aware. Each option (except function or stream options) can be set via environment variable, but local values will have precedence (if you've provided CEREBELLUM_ENV_EXEC in the environment and exec option on setupCluster, the value provided to setupCluster will be taken.)
The following options are available:
The file to be forked on clusterStart, defaults to the file calling startCluster.
Array of ommandline arguments passed to the forked worker. If set via environment variable the provided string will be split on spaces.
CEREBELLUM_ENV_ARGS="--use http"Whether or not to send output to masters stdio.
Configures the stdio of forked processes. When this option is provided, it overrides silent. For more information, have a lok here.
The number of processes to be forked. Defaults to number of cpus (os.cpus().length).
Automatically restarting forked workers if they die. Defaults to true.
Cerebellum tries to shutdown workers gracefully by giving them time to finish on there own. Here you can provide your own value in milliseconds. Default is 5000 ms.
By default the workerStarted event will be emited on the workers listening event. If you instead want to workerStarted to be emitted on online (maybe you are not running a server), you can set this to true.
log is a higher order function initialized with a worker instance.
const options = {
log: function(worker) { // <= will be executed on forking a new worker
return function(message) {
// do logging stuff here
console.log(`${worker.process.pid} => ${msg}`)
}
}
}
// or
const options = { log: worker => msg => console.log(`${worker.process.pid} => ${msg}`) }