Analysis of coroutine implementation principles in Go language

Go language is a modern programming language that has efficient concurrent programming capabilities and a lightweight threading model. In the Go language, coroutine is a lightweight way to achieve concurrency. It is a special function that can run concurrently with other coroutines. In this article, we will analyze the principles of coroutine implementation in Go language.

Coroutine implementation principle of Go language

The coroutine implementation in Go language adopts the M:N scheduling model, that is to say, M user-level threads are mapped to N kernel threads Schedule on. The biggest benefit of this scheduling model is that it can fully utilize the performance of multi-core CPUs, thereby achieving efficient concurrent processing.

In the Go language, coroutines are managed by the Go language runtime system (Goroutine Scheduler). Goroutine Scheduler is responsible for creating, destroying, scheduling coroutines, and ensuring that they run at the appropriate time. When the application starts, the Goroutine Scheduler will create a thread (goroutine), which will run as the main thread (main goroutine).

Coroutine is a lightweight thread whose scheduling and execution are managed by Goroutine Scheduler. The initial stack size of a coroutine is 2KB and can dynamically grow or shrink depending on the needs of the function being executed. When the coroutine performs a stack operation, the Goroutine Scheduler will reclaim the stack space used by the coroutine.

Goroutine Scheduler manages the running of coroutines through the scheduler. The scheduler will run under the control of Goroutine Scheduler and be responsible for managing all coroutines. For each kernel thread, the scheduler maintains a Goroutine Queue for it to save coroutines waiting to run. When a coroutine needs to run, the scheduler will take a coroutine from the coroutine queue and assign it to this kernel thread for execution. When a coroutine is suspended, it will be put back into the specified coroutine queue, waiting for the next run.

In some cases, a coroutine may be blocked, such as waiting for an I/O operation to complete. When a coroutine is blocked, the scheduler removes it from the coroutine queue and saves the coroutine's context information to a stack. When the coroutine can continue running, the scheduler restores its context information from the stack and re-adds it to the coroutine queue.

Another very important mechanism of coroutines in Go language is the channel (Channel), which is used to implement communication between coroutines. Channels are a type-safe way of exchanging data that can safely handle concurrent read and write operations. In the Go language, coroutines can synchronize certain shared resources by creating channels and performing read and write operations.

Summary

The coroutine implementation of the Go language adopts the M:N scheduling model, which manages all coroutines through the scheduler and ensures that they run at the appropriate time. Through the combination of coroutines and channels, efficient concurrent programming can be achieved. In the actual development process, the use of coroutines can greatly improve the performance and maintainability of the program. However, when using coroutines, you also need to pay attention to avoid problems such as coroutine leaks and deadlocks in order to give full play to its advantages.

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