constructor( pool = 4 ) {

		/**
		 * The size of the pool.
		 *
		 * @type {number}
		 * @default 4
		 */
		this.pool = pool;

		/**
		 * A message queue.
		 *
		 * @type {Array<Object>}
		 */
		this.queue = [];

		/**
		 * An array of Workers.
		 *
		 * @type {Array<Worker>}
		 */
		this.workers = [];

		/**
		 * An array with resolve functions for messages.
		 *
		 * @type {Array<Function>}
		 */
		this.workersResolve = [];

		/**
		 * The current worker status.
		 *
		 * @type {number}
		 */
		this.workerStatus = 0;

		/**
		 * A factory function for creating workers.
		 *
		 * @type {?Function}
		 */
		this.workerCreator = null;

	}
Constructs a new Worker pool.

@param {number} [pool=4] - The size of the pool.