Detailed explanation of the locks provided in the sync package and their implementation methods

In concurrent programming, locks are an important tool for resolving access conflicts on shared resources. The lock implementation in the sync package provided in the Go language is an important part of its concurrent programming. This article will introduce the locks provided in the sync package and their implementation methods to help readers better understand the lock mechanism in concurrent programming.

1. Lock implementation in sync package

The sync package provides three types of locks: mutex (Mutex), read-write lock (RWMutex) and wait group (WaitGroup). Their implementation methods will be introduced separately below.

1. Mutex lock (Mutex)

Mutex lock is the most basic form of lock, used to protect concurrent access to shared resources. Using a mutex lock allows only one goroutine to access a shared resource, thereby ensuring safe access to the resource. The implementation method of mutex lock can refer to the following code:

var mu sync.Mutex
var count int

func main() {
    for i := 0; i<10; i++ {
        go func(){
            mu.Lock()
            defer mu.Unlock()

            count++
            fmt.Println(count)
        }()
    }

    time.Sleep(time.Second)
}

In the above code, we use the Lock and Unlock methods in the sync.Mutex type to protect the concurrent access of the count variable. By calling the Lock method, you can obtain a mutex lock to control the number of simultaneous accesses to the resource. After executing the relevant logic, you need to call the Unlock method to release the mutex lock.

2. Read-write lock (RWMutex)

Read-write lock is a lock designed to solve the problem of more reading and less writing. In scenarios where there are many reads and few writes, the cost of using a mutex is relatively high, because locking is not required when reading shared resources. When the writing thread directly modifies the resources, locking is required.

Therefore, using read-write locks can improve the concurrency of the program. The following is an example of using a read-write lock:

var rw sync.RWMutex
var count int

func main() {
    for i := 0; i<10; i++ {
        go func(){
            rw.RLock()
            defer rw.RUnlock()

            fmt.Println(count)
        }()
    }

    time.Sleep(time.Second)
}

In the above code, we use the RLock and RUnlock methods in the sync.RWMutex type to write read operations of shared resources, and use Mutex for write operations Type's Lock and Unlock methods.

It should be noted that if the read lock is already occupied, then the write lock needs to wait for all read locks to be released before it can be acquired, and it also needs to wait for the current write lock to be released before it can acquire the read lock. Therefore, when using read-write locks, you need to consider how to use them based on the specific situation.

3. Waiting Group (WaitGroup)

Waiting group is a practical tool that allows multiple goroutines to wait for common completion.

The waiting group is initialized with a value of zero, goroutines can be added and removed, and when its internal counter reaches zero, all goroutines that are blocked and waiting will be awakened. In the following code, we use the Add and Done methods of the waiting group to control the number of goroutines:

var wg sync.WaitGroup

func main() {
    for i := 0; i<10; i++ {
        wg.Add(1)
        go func(){
            defer wg.Done()

            fmt.Println("goroutine")
        }()
    }

    wg.Wait()
    fmt.Println("finished")
}

In the above code, we first use the Add method to add 10 goroutines to the waiting group, and then add them After executing the relevant logic, use the Done method to reduce the counter of the waiting group. At the end, use the wg.Wait() method to wait for all counters in the wait group to be cleared.

2. Summary

This article introduces the lock implementation methods provided in the sync package in Go language, including mutex locks, read-write locks and wait groups. These locks are basic tools in concurrent programming in Go language and play an important role in controlling resource access and increasing program concurrency. By learning how to use them, we can better understand the lock mechanism in concurrent programming and write more efficient and safer concurrent programs.

The above is the detailed content of Detailed explanation of the locks provided in the sync package and their implementation methods. For more information, please follow other related articles on the PHP Chinese website!