人人享有性能

Author: Lin Wang (Android Performance Engineer)

作者：Lin Wang (Android 性能工程师)

Default Feature

默认功能

For mobile apps, performance is considered as the “default feature”, which means apps are expected to run fast and be responsive. It’s just as if we expect a watch to show the time. With no exceptions at Pinterest, we measure, protect and improve performance for all of our key user experiences’ surfaces, such as “Home Feed” and “Search Result Feed”.

对于移动应用，性能被视为“默认功能”，这意味着应用应该运行快速且响应迅速。就好像我们期望手表显示时间一样。在 Pinterest，没有例外，我们会测量、保护并改进所有关键用户体验’ surfaces 的性能，例如 “Home Feed” 和 “Search Result Feed”。

Hard to Measure

难以衡量

Among all the performance metrics, the user perceived latency is a crucial one. It measures how much time the user spends since they perform an action until they see the content. This is also called “Visually Complete”.

在所有性能指标中，user perceived latency 是一个关键指标。它衡量用户从执行操作到看到内容所花费的时间。这也被称为“Visually Complete”。

Visually Complete can be very different from app to app or even from surface to surface within one app. On Pinterest’s “Video Pin Closeup” surface, Visually Complete means the full-screen video starts playing; on our “Home Feed” surface, Visually Complete is defined as all the images rendered and videos playing; on our “Search Auto Complete Page”, Visually Complete refers to the search autocompleted suggestions’s text rendered along with the avatar images.

Visually Complete在不同应用中可能大相径庭，甚至在同一应用内的不同界面之间也是如此。在Pinterest的“Video Pin Closeup”界面上，Visually Complete意味着全屏视频开始播放；在我们的“Home Feed”界面上，Visually Complete定义为所有图像渲染且视频播放；在我们的“Search Auto Complete Page”上，Visually Complete指的是搜索自动完成建议的文本与头像图像一起渲染。

Given this dynamic nature of Visually Complete, engineers had to create customized measurement logic for each surface and that takes a lot of engineering effort and maintenance cost. This ends up as a major boundary for general product engineers to work on performance, especially on newly created surfaces. On average, it takes two engineer-weeks to implement a User Perceived Latency metric on the Android Client and wire it u...