程序员都需要哪些软技能

在某问答网站看到了一个非常很有意思的问题：程序员都需要哪些软技能？前段时间正好看完了一本神书，稍微归纳出一些不成熟的想法：

• 持续学习意愿
• 口头表达和写作能力
• 建立合理预期的能力
• 管理事务复杂度的能力
• 个人品牌建设的能力
• 财务管理能力

下面一一叙述。

Read More / 继续阅读

Preface

When I first saw Grafana, I was astonished by its beauty immediately and I believe it should be the very tools for most dashboard / monitor use cases. This 10,000+ stared project provide a complete solution for metrics and analytics.

Check this live demo and you should feel the same pleasure as I do.

How does Grafana work

In short, Grafana is a metric solution which include UI Render / Query / Data Source features.
UI Render is amazing; Different types of Queries are supported and it provide a wide range of Data source (mostly time series DB) support.

So, to setup a Grafana for our own use, what should we do?

• First we need to setup the data source.
• Second, we setup Grafana server and connect it with the data source.
• Thrid, we feed data into the data source

That’s it!

Setting up

The following article will cover how to set all the stuff up under Mac OSX. Although we have homebrew and pip, but it take more effort than it seems to be.

Graphite as Data Source

First of all, we are going to choose the data source first. Grafana provide a lot of DB support including: Graphite, Elasticsearch, CloudWatch, InfluxDB, OpenTSDB, KairosDB, Prometheus,

I will take Graphite as our primary data source, with the following reasons:

• powerful data APIs
• friendly render APIs with image accessing
• using whisper file to store data, operation friendly
• overall the design of Graphite is very clean, every layer of the design is scalable.

Read More / 继续阅读

最近看了一些技术项目排雷书，分几个方面总结了一下雷区，以及可以做得更好的地方。

工程质量 & 复杂度控制

• 预计变化的影响：需求会变化，系统扩展性需要加强，人员在流动。架构师的职责是管理变化，更确切的说，确保变化的影响是受控的。所以以下的技巧是必须的：
  • 只进行小型、增量的改动
  • 写可重复运行的测试用例，经常执行
  • 让编写和运行测试用例变得容易
  • 追踪依赖事项的变化
  • 自动化重复事项
• 舍弃自作聪明的设计。这样的设计让系统变得脆弱和难以维护。越老实的系统越容易扩展。
• 关注性能。假如不从一开始就严格控制性能，「暂时不用关注性能」的想法就会在团队中蔓延。很快就变成「不得不马上解决线上的性能问题」。尽早在团队里面传授性能测试工具的用法是很有效的方法，真没那个时间的话，对依赖SQL的团队，普及一下explain的使用和结果解析都会有很大的提高。
• 要评估系统的扩展性，那就尝试向多个方向增长业务规模，看看哪个方面会先支撑不住，那个就是你下个要关注的方向。
• 重视界面设计。对于产品的用户来说，用户交互界面才是系统本身。系统的响应速度提高50%当然是好事，但废老大力气的优化很容易就被糟糕的交互带来的坏心情影响。

  Read More / 继续阅读

The importance of writing unit tests have been heavily discussed. However, reality is cruel. Many developers do not write UT, and even larger amount of developers write funny tests just to pass the code coverage bar, and some developers with ambition are not quite sure about how to write good unit tests. Most good UT are written by top developers.

I thought I am that kind of ambitious developer, so I spend two weekends to start to learn it. Most cases listed below are originated from or revised from the book “Practical Unit Testing with Testng and Mockito” by Tomek Kaczanowski. A really good book worth reading.

Concepts

Before we start, let’s visit the concepts of SUT and DOC.

Read More / 继续阅读

Last weekend I went to play a reality room escape game with some friends. It’s a lot of fun and we finally escape on time!

The only thing make it less perfect is that we skip a “very hard” puzzle according to the staff in the room. We spend 1O minutes on it and we could not found an effective way to solve it.

The game is consisted of a board with 5 rows * 5 columns = 25 lights. Each light is either on or off. Player could switch any light on/off, but switching any light will also switch it’s neighbour on up/down/left/right position at the same time. The goal of this game is for a given status, try to switch some of the lights to make all the lights on.

You could also refer to this graph for the “switch logic”.

To win the game, For example, if the initial status looks like the following board (O mean an enlighted light and X mean an off light), then we could switch 2 lights on (2,1) and (4,3) to make all the light on. But is there an systematic way to get a solution?

Read More / 继续阅读

Preface

In the past 2 years, I spent about 70% of my working time to build, to break, and to fix data products. This article is a brief retrospect of my understanding on building the whole systems, as well as what kind of tools could be plugged as components.

Goal of a data System

We use data to understand reality and improve our product. This is the primary goal of a data/metric system. A good data system answers question, a better data system identifies root causes, and an even better data system help improve the whole system directly.

Use cases

In Yahoo!, the data platform I am working on mainly support a Personalization System (Recommendation system). During the iteration of the recom system, we follow and forecast what would be the actual use cases for the team to understand or to improve the Recom system. The major use cases for our system includes:

• Understand system performance with reports from different key metrics
• Detect / identify metric abnormal / data pipeline failure
• Collect user feedback data to improve system online in short cycle
• Make it easy for PM/Dev/Scientist to play with data

For different stage, we focus on different aspect and use different tools / techniques to solve problems. Let me illustrate.

Read More / 继续阅读

过年约了几个兄弟姐妹去玩桌游，大师Neo带了几个桌游过来，玩了一回合菲力猫，人到齐了以后玩了两局，，有赢有输，超级好玩。

总结一下玩了几盘以后的经验：

• 最大信息量的是投票阶段。需要记住当前的派票情况，每个人的表决是否和之前阐述理由的时候观点一致，以进行下一步的推理。多通过玩家的举动而非言语来判断玩家的身份。
• 推理身份的时候需要前提，假如在当前前提下，无法合理推出当前发生的事实（投票和任务结果），表明预设的玩家身份前提很可能错误。
• 除非特殊情况，能参与任务却投反对的很有可能是正义方，因为他觉得有邪恶方人物参与任务。但也不排除邪恶方觉得肯定无法通过投票，通过投反对进行掩饰将分配拖入下一轮。

  Read More / 继续阅读

My boss told me that my goal in this quarter is to working on Continuous Integration for our current product, and all of a sudden I think there’s a lot of gap between the goal and my current skill. The first thing came into my mind is that: “Ohhh, I am still not quite familiar with Git”. After a short period of panic, I sit down to learn about git. And here’s my note.

If you think you could learn git with manual after you learn how to branch, commit and merge, then you might probably be dispointted. Git is very flexible but it do something in a more novel way, so certain understanding of it’s internal is necessary for mastering it, and would be helpful when you look for help in manual. For example, I hear about so many terms such as “HEAD”, “Index”, “Ref”, “Staging Area”, but I could not tell exactly what is that, and I don’t even know how git works. After some diving, I wrapped something very basic in this post.

Read More / 继续阅读