[golang] synchronization lock mutex

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Synchronization lock

golang Two commonly used locks are provided .

One is sync.Mutex （ The mutex ） The other is sync.RWMutex （ Read-write lock ）

Mutex, It's the simplest and most basic synchronization lock , When one goroutine When holding a lock , Other goroutine You can only wait until the lock is released before trying to hold .

RWMutex It means read-write lock , It supports one write, many read , That is to say, it is allowed to support multiple goroutine Hold read lock at the same time , And only one is allowed goroutine Holding a write lock . When there is goroutine When holding a read lock , Will prevent write operations . When there is goroutine When holding a write lock , Both reading and writing will be blocked .

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Case study

Suppose we have more than one goroutine, But we only want to hold the lock goroutine perform , We could write it this way ：

var lock sync.Mutex

for i := 0; i < 10; i++ {
    
    go func() {
    
        lock.Lock()
        defer lock.Unlock()
        // do something
    }()
}

RWMutex Distinguish between read and write locks , So we're going to have 4 individual api, Namely Lock, Unlock, RLock, RUnlock.Lock and Unlock It's the locking and unlocking of the write lock , and RLock and RUnlock Naturally, it is the locking and unlocking of read lock .

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Interview questions

Go What are the characteristics of synchronous lock ? What is the role ？

1. Blocking . Used for data security between concurrent operations .

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