All of us are familiar with overflow bugs. However, sometimes you write code that counts on overflow. This is a story where overflow was supposed to happen but didn’t, hence the name underflow bug.

At Spotify we take user feedback seriously. We noticed some users complaining about our shuffling algorithm playing a few songs from the same artist right after each other. The users were asking “Why isn’t your shuffling random?”. We responded “Hey! Our shuffling is random!”

So who was right? As it turns out, both we and the users were right but it’s a bit more complicated than that. It also tells a nice story about how to interpret users’ feedback.

只有当我们用正确的流失数据才有可能通过分析来正确的指导决策。本文介绍的错误都是很常见的哦！​

Daniel Ek on how he spends his time, learns and makes decisions.

技术升级或者技术迁移通常很容易烂尾，一般各大公司都有不少这样的烂尾项目。怎样解决这一问题，Spotify用自己的实践给出答案。