This is a chance to perform a lot of cleanup of the page, discarding temporary objects (so that they can be reclaimed by the garbage collector) and otherwise returning the page to its pristine state.

• 这正是执行页面许多清理的一个时机，如丢弃临时对象（以便它们可以被垃圾回收器回收）、返回页面最初的状态。