'setup' 事件

每当 .setupMaster() 被调用时触发。

settings 对象是 setupMaster() 被调用时的 cluster.settings 对象,并且只能查询,因为在一个时间点内 .setupMaster() 可以被调用多次。

如果精确度十分重要,则使用 cluster.settings

Emitted every time .setupMaster() is called.

The settings object is the cluster.settings object at the time .setupMaster() was called and is advisory only, since multiple calls to .setupMaster() can be made in a single tick.

If accuracy is important, use cluster.settings.