planner: care to use errors.new and errors.errorf as your warnings and notes

[AilinKid]

Enhancement

github/pingcap/errors.git has their own encapsulation of errors.new and errors.errorf, in which their will fetch stack trace of currently places. If your generation of this errors is used like warning and note, inside which the stack trace is never necessary, so try to avoid usage of this or use another stack-less errors

[siddontang]

@AilinKid

can you give some examples about which places should not use this so others can help you improve them?

and can you also show an example of how to use a stack-less erros?

[AilinKid]

红色圈圈部分，我们在 v6.5.0 上是看不到的，为什么会在 v7.1.0 上成为性能问题呢（虽然可能整体来说占比不是很大，导致 planner 部分增长了（18.5-15.3）约占 TiDB 的 3 个点，占 planner 自身的（18.5-15.3）/18.5  = 17 个点）。研究发现，这部分基本上都是系统调用 caller的部分，主要是服务与 error.New() 和 errors.Errorf() 里面的填充的 stack 字段部分（stack: callers()）。这部分代码是 7.1 新增用来 log warning 或者 note 用的。

we did find a performance problem from internal incall concluded by a lark document in planner component, you can search the keyword by Care to use errors.New and errors.Errorf in lark app, which is not suitable to put the link here.

stack-less error is called like errors.NewNoStackError("msg")

[jackysp]

In version 7.1, I saw that in the batch write scenario, the CPU usage can reach up to 25%.

[seiya-annie]

/found customer