每个新工人都会分配一个独特的ID，这个ID会存储在id中。
id
🌐 Each new worker is given its own unique id, this id is stored in the id.
只要一个工作者还存活，这是在 cluster.workers 中索引它的关键。
cluster.workers
🌐 While a worker is alive, this is the key that indexes it in cluster.workers.