This article will explore how to use the mutex lock (Mutex) in the sync package of the Go language to control the execution of Goroutine to ensure that only one Goroutine can run at a specific time.

In concurrent programming, multiple Goroutines may access and modify shared data at the same time, which may lead to race conditions and data inconsistencies. To avoid these problems, we need to use synchronization mechanisms to protect shared resources. Mutex is a commonly used synchronization mechanism that ensures that only one Goroutine can access protected resources at the same time.

Using sync.Mutex

The sync package of the Go language provides the Mutex type, which implements the function of a mutex lock. The Mutex type has two methods:

• Lock(): Try to acquire the lock. If the lock is already held by another Goroutine, the current Goroutine will block until the lock is released.
• Unlock(): Release the lock. Only the Goroutine holding the lock can release the lock.

Here is a simple example that demonstrates how to use a Mutex to protect shared variables:

 package main

import (
    "fmt"
    "sync"
    "time"
)

var (
    counter int
    mutex sync.Mutex
)

func increment() {
    for i := 0; i <p> In this example, counter is a shared variable and mutex is a mutex lock. The increment() function will loop 1000 times. Each loop will first acquire the lock, then increase the value of counter, and finally release the lock. By using a mutex, we can ensure that only one Goroutine can modify the value of counter at the same time, thereby avoiding race conditions.</p><h3> Multiple Goroutine serial execution</h3><p> In addition to protecting shared resources, mutex locks can also be used to control the execution order of multiple Goroutines to ensure that they execute in a specific order. Here is an example that demonstrates how to use a mutex to control serial execution of multiple Goroutines:</p><pre class="brush:php;toolbar:false"> package main

import (
    "fmt"
    "sync"
)

func main() {
    var mutex sync.Mutex
    var wg sync.WaitGroup

    numRoutines := 3

    wg.Add(numRoutines)

    for i := 1; i <p> In this example, we create three Goroutines. Each Goroutine will first acquire the lock, then print a message, and finally release the lock. Due to the existence of the mutex lock, these three Goroutines will be executed in sequence instead of concurrently.</p><h3> Things to note</h3>

• Avoid deadlock : When using mutex locks, special attention needs to be paid to avoid deadlock. Deadlock refers to two or more Goroutines waiting for each other to release the lock, causing the program to be unable to continue execution. In order to avoid deadlock, you should try to avoid trying to acquire the lock again while holding the lock, or use sync.RWMutex read-write lock, which allows multiple Goroutines to read shared resources at the same time, but only allows one Goroutine to write to shared resources.
• Release the lock promptly : When using a mutex, it is important to ensure that the lock is released promptly when it is no longer needed. If the lock is not released, other Goroutines will continue to block, resulting in reduced program performance. You can use the defer statement to ensure that the lock is released when the function exits.
• Consider performance : Mutex locks will bring certain performance overhead, so excessive use of mutex locks should be avoided. In some cases, other synchronization mechanisms, such as atomic operations or channels, can be used instead of mutexes to improve program performance.

Summarize

Mutex lock is a commonly used synchronization mechanism in the Go language. It can be used to protect shared resources and control the execution order of Goroutine. When using mutex locks, you need to pay attention to avoiding deadlocks, releasing locks in time and considering performance. By properly using mutex locks, you can write safe and efficient concurrent programs.

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