Go Standard library--sync. Mutex Mutex

a mutex is a mutex that can be created as a field for other structures, and a value of 0 is the unlocked state. The lock of the Mutex type is not thread-independent, and can be loads and unlocked by different lines.

Method

Func (*mutex) Lock

func (m *Mutex) Lock()

The Lock method locks m, and if M is already locked, it blocks until M unlocks.

Func (*mutex) Unlock

func (m *Mutex) Unlock()

The Unlock method unlocks m, which causes a run-time error if M is not locked.

Attention

• After a goroutine obtains the mutex, the other goroutine can only wait until the Goroutine releases the mutex

After using lock (), you can no longer lock it until you unlock it with Unlock ().

• Using Unlock () before Lock () causes panic exceptions
• A locked Mutex is not associated with a specific goroutine, so it can be locked with one goroutine and then unlocked with another goroutine
• Lock again before the Mutex in the same goroutine is unlocked, causing a deadlock
• For read-write uncertainties, and only one read or write scenario

Instance

package mainimport (    "fmt"    "sync"    "time")func main() {    var mutex sync.Mutex    wait := sync.WaitGroup{}    fmt.Println("Locked")    mutex.Lock()    for i := 1; i <= 3; i++ {        wait.Add(1)        go func(i int) {            fmt.Println("Not lock:", i)            mutex.Lock()            fmt.Println("Lock:", i)            time.Sleep(time.Second)            fmt.Println("Unlock:", i)            mutex.Unlock()            defer wait.Done()        }(i)    }    time.Sleep(time.Second)    fmt.Println("Unlocked")    mutex.Unlock()    wait.Wait()}

Operation Result:

LockedNot lock: 1Not lock: 2Not lock: 3UnlockedLock: 1Unlock: 1Lock: 2Unlock: 2Lock: 3Unlock: 3

Reference

• Standard library document--sync. Mutex
• Golang in sync. Mutex and sync. Rwmutex

Original address: Https://shockerli.net/post/go

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