The difference between golang coroutines

Go language is a programming language that has attracted much attention in recent years. Its unique concurrent programming method and coroutine mechanism are widely used in Web development, system programming, network communications and other fields. In the Go language, a coroutine is a lightweight thread that is managed by the Go language runtime and can execute tasks concurrently in the program.

In the Go language, a coroutine is a function or method followed by the "go" keyword, which can be executed concurrently with other coroutines. Coroutines are characterized by being lightweight, efficient, and scalable. In the Go language, there are two different implementations of coroutines: coroutines based on user-level threads and coroutines based on operating system threads. These two implementation methods have different advantages and disadvantages, and play different roles in different application scenarios.

User-level thread-based coroutine

User-level thread-based coroutine is a coroutine mechanism implemented in the user program. It uses the "m:" in the Go language runtime: n" coroutine model implementation, that is, m user-level threads are mapped to n operating system threads. Each coroutine in the user program will be executed on a different user-level thread, and these threads are managed by the "scheduler" in the Go language runtime. Each user-level thread maintains a coroutine queue. Under the scheduling of the scheduler, different user-level threads will take turns executing the coroutines in the queue.

The coroutine mechanism based on user-level threads is called "goroutine" in the Go language and is the main implementation method of coroutines in the Go language. Compared with traditional threads, "goroutine" is more efficient, scalable, and lightweight, and can execute a large number of coroutines at the same time, thereby improving the system's concurrent processing capabilities.

Coroutine based on operating system threads

Coroutine based on operating system threads is a coroutine mechanism implemented at the operating system level. It is implemented using the "1:1" coroutine model in the Go language runtime, which maps each coroutine to a thread in the operating system. In the Go language, operating system threads and coroutines have a one-to-one correspondence, and each coroutine has its own operating system thread.

The coroutine mechanism based on operating system threads is called "thread" in Go language and is another implementation method of coroutine in Go language. Compared with "goroutine", "thread" has higher controllability and stability, but its creation and destruction cost is relatively high, which may cause a waste of system resources in large-scale concurrency scenarios.

Selection of coroutines

When using Go language coroutines, we need to choose different coroutine implementation methods according to the actual situation. Generally speaking, for short-term, lightweight concurrent processing tasks, we can use "goroutine" based on user-level threads; and for long-term, heavyweight concurrent processing tasks, we can use "threads" based on operating system threads. ".

In practical applications, we can create coroutines through the "go" keyword. For example:

go func() {
    // do something
}()

In this example, we use the "go" keyword to create an anonymous coroutine, which will execute concurrently with other coroutines in the background.

In addition, the Go language also provides a wealth of coroutine processing tools and libraries, such as "channel", "select", "sync", etc. These tools and libraries can help us process coroutines more conveniently. communication, synchronization and other issues.

Summary

Coroutine is a lightweight thread in the Go language that can achieve efficient concurrent processing. In the Go language, there are two different implementations of coroutines: "goroutine" based on user-level threads and "threads" based on operating system threads. We need to choose different coroutine implementation methods according to the actual situation to achieve more efficient and scalable concurrent processing. At the same time, when using coroutines, we also need to pay attention to issues such as communication and synchronization between coroutines to ensure the correctness and stability of the program.

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