A queue that is dequeued by forked processes
ForkQueue creates a queue where the items are removed via a 'next' message received from child processes. The number of child processes is passed to the constructor along with the full path of the module to run. The processes are spawned via child_process.fork
var Queue = ;var numWorkers = 5module = 'worker.js';var queue = numWorkers module;
Add a value to the queue
for var i = 0; i < 100; i++queue;
Puts the values of the array onto the queue
var vals = ;for var i = 0; i < 100; i++vals;queue;
Wait for the child processes to work through the queue then kill them.
The Queue inherits from EventEmitter. It emits the following events:
queue.emit('msg', value)- a value forwarded from a worker
queue.emit('error', error)- an error
queue.emit('enqueue', value)- the enqueued value
queue.emit('dequeue', value)- the dequeued value
queue.emit('concat', values)- the list of values to enqueue
queue.emit('flush')- the queue is trying to flush outstanding tasks to available workers
Worker modules are spawned with child_process.fork. In order to request a value off the queue, they send a 'next' message to the parent with
process.send('next'). The only message sent to them contains the value off the queue. They will exit with 'SIGTERM' sent from the parent after
queue.end is called. They can also send arbitrary messages != 'next', that get emitted from the queue.
A simple worker is below.