当您的应用程序在后台运行时，用户根本不会参与"该应用程序.使用较新版本的Android，操作系统可能会随时在没有警告的情况下立即杀死您的后台应用程序，因此，计算有意义的后台时间指标甚至更加困难.在我看来，就分析而言，背景时间几乎是毫无意义的指标. 背景时间在Firebase性能监控中很有用，但是应用性能在这方面与分析不同.

When your app is in the background, the user isn't "engaged" with it at all. With newer versions of Android, the OS may immediately kill your backgrounded app at any time without warning, so it's even more difficult to calculate a meaningful metric for background time. It seems to me that background time is a mostly meaningless metric, in terms of analytics. Background time has a use in Firebase Performance Monitoring, but app performance in this respect isn't the same as analytics.