worker.cpuUsage([prev])

• 返回：<Promise>

该方法返回一个 Promise，该 Promise 会解析为与 process.threadCpuUsage() 相同的对象，或者如果工作线程不再运行，则会以 ERR_WORKER_NOT_RUNNING 错误拒绝。该方法允许从实际线程外部观察统计信息。

【This method returns a Promise that will resolve to an object identical to process.threadCpuUsage(), or reject with an ERR_WORKER_NOT_RUNNING error if the worker is no longer running. This methods allows the statistics to be observed from outside the actual thread.】