Introduction to lock types and application methods of Golang functions

Introduction to lock types and application methods of Golang functions

The Go programming language is an efficient, scalable, and concurrency-safe language, and concurrency safety is a highlight of Golang. We usually use locks to ensure thread safety during development. Golang's standard library provides multiple types of locks for different scenarios. In this article, we will introduce the lock types of Golang functions and how to apply them.

1. Mutex (mutex lock)

Mutex lock is used to protect shared resources. Only one thread is allowed to enter the critical section at a time, and other threads must wait for the locked resource. The thread releases the lock. Mutex (mutex) is the most basic lock type and can be implemented through the sync.Mutex structure in Golang.

Mutex constructor:

var mu sync.Mutex

The following is the sample code for Mutex locking and unlocking:

mu.Lock()
// 临界区代码
mu.Unlock()

Mutex is suitable for any scenario of shared resource access, using Mutex can provide Good thread safety, but it can also introduce problems such as deadlocks.

2. RWMutex (read-write lock)

Read-write lock is an upgraded version of Mutex. RWMutex is similar to Mutex in use, but has the characteristics of reading and writing separation. RWMutex can allow multiple threads to read critical section code at the same time, but only allows one thread to write to shared resources.

RWMutex constructor:

var mu sync.RWMutex

The following is a sample code for RWMutex's read and write separate locking and unlocking:

// 读锁定和解锁
mu.RLock()
// 读临界区代码
mu.RUnlock()

// 写锁定和解锁
mu.Lock()
// 写临界区代码
mu.Unlock()

RWMutex is suitable for reading operations more frequently than writing operations Shared resources, the read-write separation feature it provides can improve concurrency performance.

3. WaitGroup (Waiting Group)

WaitGroup is a counting semaphore that can be used to wait for one or more threads to complete a task. A common use of WaitGroup is to wait in the main thread for all child threads to complete their tasks before proceeding to the next step.

WaitGroup constructor:

var wg sync.WaitGroup

The following are common uses of WaitGroup:

// 添加一个任务
wg.Add(1)

// 完成一个任务
wg.Done()

// 等待所有任务完成
wg.Wait()

WaitGroup can solve resource coordination problems, but it may also cause deadlock problems, so it is necessary to Use with caution.

4. Cond (condition variable)

Cond is a condition variable used for inter-thread communication. It can prevent one or more threads from continuing execution until specific conditions are met.

Cond constructor:

var cond sync.Cond

The following are common ways to use Cond:

// 等待条件满足
cond.Wait()

// 唤醒所有等待条件的线程
cond.Broadcast()

// 唤醒一个等待条件的线程
cond.Signal()

Using Cond requires caution, as deadlock problems are prone to occur.

5. Once (one-time execution)

Once provides a one-time execution function, which ensures that a function will only be executed once. Once is often used in scenarios such as initialization and resource management.

Once constructor:

var once sync.Once

Common usage of Once:

once.Do(func() {
    // 只执行一次的代码
})

Using Once can easily ensure that a function is executed only once.

Summary

Golang’s standard library provides multiple types of locks for thread synchronization and collaboration in different scenarios. Being proficient in the use of various types of locks can improve the concurrency performance of the program. At the same time, you need to pay attention to deadlock problems that may occur during the locking process.

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