我在谷歌上搜索了一下Go的网站,但我找不到Go非凡的构建时间的解释。它们是语言特性(或缺乏特性)的产物、高度优化的编译器还是其他什么?我并不是在推广围棋;我只是好奇。


当前回答

Go对所有文件导入一次依赖项,因此导入时间不会随着项目大小呈指数增长。 更简单的语言学意味着解释它们需要更少的计算。

还有什么?

其他回答

Go编译器比大多数C/ c++编译器快得多的原因有很多:

Top reason: Most C/C++ compilers exhibit exceptionally bad designs (from compilation speed perspective). Also, from compilation speed perspective, some parts of the C/C++ ecosystem (such as editors in which programmers are writing their code) aren't designed with speed-of-compilation in mind. Top reason: Fast compilation speed was a conscious choice in the Go compiler and also in the Go language The Go compiler has a simpler optimizer than C/C++ compilers Unlike C++, Go has no templates and no inline functions. This means that Go doesn't need to perform any template or function instantiation. The Go compiler generates low-level assembly code sooner and the optimizer works on the assembly code, while in a typical C/C++ compiler the optimization passes work on an internal representation of the original source code. The extra overhead in the C/C++ compiler comes from the fact that the internal representation needs to be generated. Final linking (5l/6l/8l) of a Go program can be slower than linking a C/C++ program, because the Go compiler is going through all of the used assembly code and maybe it is also doing other extra actions that C/C++ linkers aren't doing Some C/C++ compilers (GCC) generate instructions in text form (to be passed to the assembler), while the Go compiler generates instructions in binary form. Extra work (but not much) needs to be done in order to transform the text into binary. The Go compiler targets only a small number of CPU architectures, while the GCC compiler targets a large number of CPUs Compilers which were designed with the goal of high compilation speed, such as Jikes, are fast. On a 2GHz CPU, Jikes can compile 20000+ lines of Java code per second (and the incremental mode of compilation is even more efficient).

编译效率是主要的设计目标:

最后,它的目的是要快:在一台计算机上构建一个大型可执行文件最多只需要几秒钟。为了实现这些目标,需要解决一些语言问题:表达性强但轻量级的类型系统;并发性和垃圾回收;刚性依赖规范;等等。常见问题解答

关于与解析相关的特定语言特性,语言常见问题解答非常有趣:

第二,该语言被设计成易于分析,并且可以在没有符号表的情况下进行解析。

虽然上面的大部分都是正确的,但有一点非常重要,没有被真正提到:依赖管理。

Go只需要包含您直接导入的包(就像那些已经导入的包一样)。这与C/ c++形成鲜明对比,在C/ c++中,每个文件都包含x头文件,其中包含y头文件等等。总结:Go的编译需要线性时间w.r.t到导入包的数量,而C/ c++需要指数级的时间。

摘自Alan Donovan和Brian Kernighan所著的《the Go Programming Language》一书:

Go compilation is notably faster than most other compiled languages, even when building from scratch. There are three main reasons for the compiler’s speed. First, all imports must be explicitly listed at the beginning of each source file, so the compiler does not have to read and process an entire file to determine its dependencies. Second, the dependencies of a package form a directed acyclic graph, and because there are no cycles, packages can be compiled separately and perhaps in parallel. Finally, the object file for a compiled Go package records export information not just for the package itself, but for its dependencies too. When compiling a package, the compiler must read one object file for each import but need not look beyond these files.

编译的基本思想实际上非常简单。原则上,递归下降解析器可以以I/O限制的速度运行。代码生成基本上是一个非常简单的过程。符号表和基本类型系统并不需要大量的计算。

然而,降低编译器的速度并不难。

如果存在一个预处理器阶段,其中包含多级包含指令、宏定义和条件编译,尽管这些东西很有用,但加载它并不难。(举个例子,我想到了Windows和MFC头文件。)这就是为什么预编译头文件是必要的。

在优化生成的代码方面,可以向该阶段添加多少处理是没有限制的。