// & takes the address of an object.

// +build prod, dev, test

Containerization solves these proble

lets you to control the sampling rate of the CPU profiler

The example above is highly simplified and omits many details around return values, frame pointers, return addresses and function inlining. In fact, as of Go 1.17, the program above may not even need any space on the stack as the small amount of data can be managed using CPU registers by the compiler

recommend disabling optimizations when building the code being debugged

Go users can create their custom profiles via pprof.Profile and use the existing tools

I want a tiny binary, for a monitoring/logging agent, or a systems tool like docker agent, or kubectl, fantastic, Go (or Rust) is the best language to go for. I want to make REST APIs, and some DB calls - no worse choices than Go to do that. Even Python and Node are far better

Project Structure

在新版本（起码 1.15 及以后）的 Go 当中，sync.Pool 里的临时对象需要两次 GC 才会被真正清除掉。 // 只一次 GC 的话只会让其中的临时对象被“打上记号”。 // 更具体的说，只做一次 GC 只会使得 sync.Pool 里的临时对象被移动到池中的“备用区域”（详见 victim 字段）。 // 在我们调用 sync.Pool 的 Get 方法时，如果 sync.Pool 的“本地区域”（详见 local 字段）当中没有可用的临时对象， // 那么 sync.Pool 会试图从这个“备用区域”中获取临时对象。 // 如果“备用区域”也没有可用的临时对象，sync.Pool 才会去调用 New 函数。 // 所以，这里的例子需要再添加一行对 runtime.GC() 函数的调用，才能使它的结果与最初的相同，并起到准确示范的作用。

Setting up your workspace

slice深拷贝和浅拷贝

It’s important to understand that even though a slice contains a pointer, it is itself a value. Under the covers, it is a struct value holding a pointer and a length. It is not a pointer to a struct.

那为什么在上面的场景中，atomic会比mutex性能好很多呢？作者 Dmitry Vyukov 总结了这两者的一个区别： Mutexes do no scale. Atomic loads do. Mutex由操作系统实现，而atomic包中的原子操作则由底层硬件直接提供支持。在 CPU 实现的指令集里，有一些指令被封装进了atomic包，这些指令在执行的过程中是不允许中断（interrupt）的，因此原子操作可以在lock-free的情况下保证并发安全，并且它的性能也能做到随 CPU 个数的增多而线性扩展。

we should never blindly apply dogmatic advice, and that we should use our judgment each and every time.

If the word “share” doesn’t come out of your mouth, you don’t need to use a pointer

The benefit of passing data “by value” is readability. The value you see in the function call is what is copied and received on the other side

Functions execute within the scope of frame boundaries that provide an individual memory space for each respective function. Each frame allows a function to operate within their own context and also provides flow control. A function has direct access to the memory inside its frame, through the frame pointer, but access to memory outside its frame requires indirect access. For a function to access memory outside of its frame, that memory must be shared with the function.

The log will become something of a commoditized interface, with many algorithms and implementations competing to provide the best guarantees and optimal performance.

Go Programming Language publicly in 2009 they were also looking to solve certain challenges of the existing Computer languages. Of the many features that it demonstrated (we will get to those soon enough) it was also helpful in addressing the strange dilemma of hardware and software that was emerging.

(It's usually a mistake to pass back the concrete type of an error rather than error, for reasons discussed in the Go FAQ, but it's the right thing to do here because ServeHTTP is the only place that sees the value and uses its contents.)

There are two reasons for having no warnings. First, if it's worth complaining about, it's worth fixing in the code.

[]byte