Mastering Go's runtime: from compilation to execution

Explain the full cycle process of Go language from compilation to execution. Each part will contain rich technical details and actual code examples to help everyone understand.

Follow TechLead to share full-dimensional knowledge of Internet architecture and cloud service technology. The author has 10+ years of Internet service architecture, AI product development experience, and team management experience. He holds a master's degree from Tongji University in Fudan University, a member of Fudan Robot Intelligence Laboratory, a senior architect certified by Alibaba Cloud, a project management professional, and research and development of AI products with revenue of hundreds of millions. principal.

1. Introduction to Go running and compiling

The Go language (also known as Golang) has become an integral part of modern software development since it was released by Google in 2009. Designers Rob Pike, Ken Thompson, and Robert Griesemer address real-world programming problems caused by multi-core processors, networked systems, and large code bases. In this section, we will delve into the core thinking points of Go language in terms of running and compilation.

The Goals and Design Philosophy of the Go Language

The goal of the Go language is to achieve the perfect balance of high performance, productivity, and software quality. In order to achieve this goal, designers have made key considerations in the following aspects:

1. Simplicity : Making a language easier to learn and use by reducing the number of language features.
2. High performance : It is necessary to achieve an execution speed similar to that of C/C++, but also to have a development cycle as fast as Python.
3. Concurrency support : Native support for concurrent programming, taking full advantage of modern multi-core processors.

runtime environment

Go's runtime environment is carefully designed for efficient execution, concurrency, and garbage collection. The designers paid special attention to the following points in this regard:

1. Lightweight threads (Goroutines) : Designers considered how to effectively implement concurrency, not just through the traditional threading model. Goroutines are more lightweight than operating system threads and can utilize system resources more efficiently.

2. Memory management : The Go runtime includes a garbage collector to automatically manage memory. Designers have put a lot of optimization work into the selection and implementation of garbage collection algorithms to reduce latency and improve performance.

3. Network I/O : Go's runtime environment also includes efficient network I/O support to simplify network programming and optimize performance.

Compilation process

Go language pays special attention to compilation speed. The following are several main thinking points:

1. Dependency analysis : Go's package management and dependency resolution mechanism is simple and efficient, making the entire compilation process very fast.

2. Just-in-time compilation and static compilation : The Go compiler supports fast just-in-time compilation and generates statically linked executable files, reducing the time and resources required to parse and load shared libraries at runtime.

3. Cross-platform : Designers ensured that the Go compiler could easily generate code for different operating systems and architectures.

4. Optimization : Although the Go compiler emphasizes compilation speed, the designers also put a lot of effort into the optimization of the generated machine code.

summary

Overall, the designers of the Go language made a lot of thoughtful decisions in terms of runtime and compilation to achieve the perfect combination of performance, simplicity, and usability. This is also one of the key factors why Go can quickly emerge and become a major player in modern programming languages.

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2. Execution environment

The execution environment of the Go language not only covers the runtime system, but also includes the interaction between the underlying operating system and hardware. This environment is the core of Go's high-performance, high-concurrency performance. This section will provide an in-depth analysis of the execution environment of the Go language from many aspects.

Operating system and hardware layer

System calls (Syscalls)

The Go language encapsulates system calls so that programs can run seamlessly on different operating systems (such as Linux, Windows and macOS). These encapsulation processes interact with the operating system through assembly code or C language.

Virtual Memory

Go's memory management is closely tied to the operating system's virtual memory system. This includes page size, page alignment, and memory allocation using mmapor corresponding system calls.

Go runtime (Runtime)

Goroutine scheduler

The Go language runtime includes a built-in Goroutine scheduler. This scheduler uses an M:N model, where M are operating system threads and N are Goroutines.

1. GMP model : Go's scheduling model is based on G (Goroutine), M (Machine, i.e. OS thread) and P (Processor, i.e. virtual CPU). P represents the resource that can run Goroutine.

2. Work Stealing : In order to utilize multi-core CPUs more effectively, Go's scheduler adopts a work stealing algorithm so that idle P can "steal" the tasks of other Ps.

Memory management and garbage collection

Go's runtime includes a garbage collector that is concurrent and parallel.

1. Tri-color Mark and Sweep : Go uses the Tri-color algorithm for garbage collection.

2. Write Barrier : Go's GC also uses write barrier technology to support concurrent garbage collection.

3. Escape Analysis : During compilation, Go performs escape analysis to determine which variables need to be allocated on the heap and which can be allocated on the stack.

Network I/O

Go's network I/O model is event-driven.

1. Epoll/Kqueue : On Unix-like systems, Go uses Epoll (Linux) or Kqueue (BSD, macOS) to implement efficient network I/O.

2. Non-blocking I/O : The Go runtime sets all I/O operations to non-blocking mode and manages them through the Goroutine scheduler, achieving the effect of asynchronous I/O.

Code Example: Go Runtime Scheduling

// 使用Goroutine进行简单的任务调度
go func() {
    
    
    fmt.Println("Hello from Goroutine")
}()

Output:

Hello from Goroutine

deep thinking

1. Scalability and Microservices : Go’s execution environment design makes it ideally suited for microservices architecture. Efficient Goroutine scheduling and network I/O handling mean that Go can easily scale to handle large numbers of concurrent requests.

2. Garbage collection and latency-sensitive applications : Although Go's garbage collector is optimized, garbage collection may still be a concern in extremely latency-sensitive application scenarios.

3. Cross-platform challenges and opportunities : Although Go aims to be a cross-platform programming language, execution performance and behavior may vary on different operating systems and hardware architectures.

By in-depth understanding of Go's execution environment, developers can more effectively utilize Go's powerful features to solve practical problems. It also helps to understand how the Go language achieves its excellent performance and flexibility.

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3. Compilation and linking

Both the Go language compiler and linker are crucial components in the Go language ecosystem. They not only ensure that code can be efficiently converted into machine instructions, but also ensure that different code modules can be combined correctly. This section will analyze various aspects of Go compilation and linking in detail.

Go compiler

Lexical, grammatical analysis and intermediate representation

The compiler first performs lexical analysis and syntax analysis to generate an abstract syntax tree (AST). Next, the AST is converted into a more concise intermediate representation (IR).

type checking

The Go compiler performs strict type checking at compile time, including but not limited to interface implementation, use of null values, and variable initialization.

optimization

The compiler will perform various optimizations on IR, including constant folding, dead code elimination, loop unrolling, etc.

code generation

The compiler will finally convert the optimized IR into machine code for the target platform.

Go linker

Symbol parsing

The Go linker first parses the symbol tables in various code modules (usually .oor files) to determine which symbols are external and which are internal..a

Dependency resolution and package management

Go uses a specific package management strategy that allows static and dynamic linking. Go Modules is now the officially recommended dependency management tool.

final code generation

The linker finally combines all code modules and dependent libraries into a single executable file.

Code Example: Compiling and Linking

# 编译Go代码
go build main.go

# 编译并生成静态链接的可执行文件
CGO_ENABLED=0 go build -o static_main main.go

deep thinking

1. Compilation speed and optimization : Go emphasizes fast compilation, but does this limit the compiler from performing deeper optimizations? This is a trade-off.

2. Package management and version control : Go Modules provide a modern solution for dependency management, but in large, complex code bases, version management can become complicated.

3. Static and dynamic linking : Go usually generates statically linked executable files, which greatly simplifies deployment, but also brings problems such as larger executable files and difficulty in dynamic updates.

4. Cross-platform compilation : Go supports cross-compilation, which is one of its powerful aspects, but may also bring target platform-specific issues, such as system calls and hardware optimizations.

By understanding Go's compilation and linking process, developers can not only solve problems more effectively, but also gain a deeper understanding of the underlying principles and design ideas of the language, thereby writing more efficient and maintainable code.

4. Execution model

The execution model of the Go language refers to how each code block is executed when the program is running. From the beginning of program execution to the end, the involved function calls, stack frame management, and exception handling all constitute Go's execution model. This section will delve into the execution model of the Go language.

main function

In a Go program, execution starts with maina function. When the program runs, the Go runtime calls mainthe function as the entry point of the program. Starting from mainthe function, the execution path of the program jumps between functions until mainthe function returns or an exception occurs.

Initialization process

Go’s initialization process includes:

1. Import packages : Go will mainimport the required packages step by step starting from the function to ensure that the dependencies are met.

2. Initialize package-level variables : Global variables in each package will be initialized. If there are multiple packages, they will be initialized in order of dependency.

3. Execution initfunctions : The functions in each package initwill be executed in the order of import to complete some initialization work.

Function call and return

The Go language uses the stack to manage function calls and returns. When a function is called, a new stack frame is allocated on the stack. The stack frame stores function parameters, local variables, and the return address of the function call. When the function execution is completed, the stack frame is popped and control returns to the calling function.

defer function

An important feature of Go's execution model is the delay function. With deferkeywords, you can defer function execution until the end of the function in which it is located. This is very useful in resource release, error handling, etc.

Recursion and tail call optimization

Go supports recursive function calls. Although Tail Call Optimization is not part of Go, understanding recursion and tail call optimization can help understand some details in the execution model.

deep thinking

1. Function call overhead and stack space : Although Go's function call overhead is relatively low, stack space may be exhausted during recursion. How to avoid stack overflow while maintaining recursive thinking is an issue that needs attention.

2. Delay functions and resource management : The use of delay functions is an elegant way of resource management, but it may require special attention when dealing with situations that require immediate release of resources.

3. Initialization and startup performance : For some small applications, Go's initialization and startup may seem a little time-consuming. Understanding these processes can help you design more responsive applications.

By in-depth understanding of Go's execution model, developers can make better use of features such as functions, calls, and delays, as well as methods such as optimizing recursion and reducing delayed function calls, to write efficient and readable Go code.

Follow TechLead to share full-dimensional knowledge of Internet architecture and cloud service technology. The author has 10+ years of Internet service architecture, AI product development experience, and team management experience. He holds a master's degree from Tongji University in Fudan University, a member of Fudan Robot Intelligence Laboratory, a senior architect certified by Alibaba Cloud, a project management professional, and research and development of AI products with revenue of hundreds of millions. principal.