What are the synchronization mechanisms between golang functions and goroutine?

Go language provides a variety of synchronization mechanisms, including mutex locks, read-write locks, condition variables and WaitGroup, to solve data inconsistencies or race conditions caused by concurrent access to shared resources. Mutex locks provide exclusive access to shared resources, read-write locks support multiple simultaneous reads and single writes, condition variables are used to coordinate waiting and notification between Goroutines, and WaitGroup is used to wait for a group of Goroutines to complete. For example, in the case of a shared buffer, a mutex can ensure that only one Goroutine accesses the buffer at a time, avoiding data corruption.

The synchronization mechanism of functions and Goroutines in Go language

In concurrent programming, the synchronization mechanism is crucial and is used to Ensure that concurrent access to shared resources does not cause data inconsistencies or race conditions. The Go language provides a variety of synchronization mechanisms. The following are the most commonly used mechanisms for synchronizing functions and Goroutines:

Mutex (Mutex)

Mutex locks provide Exclusive access to shared resources. When a Goroutine acquires a mutex, other Goroutines will be blocked until the Goroutine releases the mutex.

var mu sync.Mutex

func someFunction() {
    mu.Lock()
    // 对共享资源进行操作
    mu.Unlock()
}

Read-write lock (RWMutex)

Read-write lock allows multiple Goroutines to read shared resources at the same time, but only one Goroutine can write to shared resources at the same time.

var rwmu sync.RWMutex

func someFunction() {
    rwmu.RLock()
    // 读取共享资源
    rwmu.RUnlock()
}

func anotherFunction() {
    rwmu.Lock()
    // 写入共享资源
    rwmu.Unlock()
}

Condition variable (Cond)

Condition variable is used to coordinate waiting and notification between Goroutines. A Goroutine can wait on a condition variable until another Goroutine notifies it.

var cond sync.Cond

func someFunction() {
    cond.L.Lock()
    // 等待条件变量被通知
    cond.Wait(&cond.L)
    // 执行被通知后的代码
    cond.L.Unlock()
}

func anotherFunction() {
    cond.L.Lock()
    // 通知正在等待条件变量的 Goroutine
    cond.Signal()
    cond.L.Unlock()
}

WaitGroup

WaitGroup is used to wait for a group of Goroutines to complete. It ensures that certain operations are not performed until all Goroutines have completed.

var wg sync.WaitGroup

func someFunction() {
    wg.Add(1)

    // Goroutine 执行一些任务

    wg.Done()
}

func main() {
    wg.Add(5)

    for i := 0; i < 5; i++ {
        go someFunction()
    }

    // 等待所有 Goroutine 完成
    wg.Wait()

    // 主 Goroutine 执行一些操作
}

Practical case

Take a shared buffer as an example. Multiple Goroutines read and write data from the buffer. We can use a mutex to ensure concurrent access to the buffer:

var mu sync.Mutex
type Buffer struct {
    data []int
}

func (b *Buffer) Read() []int {
    mu.Lock()
    defer mu.Unlock()

    return b.data
}

func (b *Buffer) Write(data []int) {
    mu.Lock()
    defer mu.Unlock()

    b.data = data
}

By using a mutex, we ensure that at any given time, only one Goroutine can access the shared buffer, thus avoiding data damage.

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