What is golang synchronization method?

With the continuous updating and development of computer technology, programming languages ​​are also constantly updated and evolved. An important feature of programming languages ​​is to support concurrent execution of multiple threads. During the concurrent execution of multiple threads, it is easy for different threads to interfere with each other or access the same resource at the same time. In this case, synchronization methods need to be used to solve the problem.

Golang is a programming language that supports multi-threaded concurrency. Many Golang programmers use synchronization methods to solve concurrent access problems. This article will lead readers to understand the use of Golang synchronization methods.

Introduction to synchronization methods

In Golang, the use of synchronization methods can ensure data synchronization between different coroutines and data access security between multiple coroutines. By using synchronization methods, programmers can avoid data access conflicts when multiple coroutines execute concurrently. In Golang, there are many ways to implement synchronization methods, including mutex locks, rwmutex locks, channels, etc.

mutex lock

Mutex lock is the most basic synchronization method in Golang. It provides the most basic data synchronization method. The use of mutex lock is very simple. You only need to add mutex lock before the coroutine to achieve the purpose of coroutine synchronization. The following is a sample code using mutex lock:

package main

import (
    "fmt"
    "sync"
)

var (
    count int
    lock sync.Mutex
)

func increment() {
    lock.Lock()
    count++
    lock.Unlock()
}

func main() {
    var wg sync.WaitGroup
    for i := 0; i < 1000; i++ {
        wg.Add(1)
        go func() {
            defer wg.Done()
            increment()
        }()
    }
    wg.Wait()
    fmt.Println(count)
}

In the above code, we use sync.Mutex to achieve coroutine synchronization. In the increment function, we use lock.Lock and lock.Unlock to lock count, ensuring that when multiple coroutines access count, only one coroutine can access it, avoiding data conflicts caused by concurrent access. In the main function, we open 1000 coroutines to call the increment function and finally output the value of count.

rwmutex lock

Although mutex lock can solve the problem of concurrent access conflicts, in some scenarios, it needs to support both read operations and write operations. At this time, you need to use rwmutex lock. The rwmutex lock in Golang is a read-write lock, which divides the lock into two types: read lock and write lock. The read lock can be held by multiple coroutines at the same time, but when the write lock is held, the read lock cannot be acquired, that is, the write lock has a higher priority than the read lock.

The following is a sample code using rwmutex lock:

package main

import (
    "fmt"
    "sync"
)

var (
    count int
    lock sync.RWMutex
)

func read() {
    lock.RLock()
    defer lock.RUnlock()
    fmt.Println(count)
}

func write() {
    lock.Lock()
    defer lock.Unlock()
    count++
}

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

    wg.Add(1)
    go func() {
        defer wg.Done()
        write()
    }()
    wg.Wait()
}

In the above code, we define a count variable and a sync.RWMutex, and use the read and write functions to read Write the count variable. When the read function is called, we use lock.RLock to obtain the read lock so that multiple coroutines can read the value of the count variable at the same time. When the write function is called, we use lock.Lock to obtain the write lock so that only one coroutine can write the value of the count variable. In the main function, we open 10 coroutines to call the read function, and one coroutine to call the write function.

channel

In addition to mutex lock and rwmutex lock, there is another synchronization method in Golang, which is channel. Channels can be used to transfer data between coroutines and synchronize the execution order of coroutines. There are three types of channels: unbuffered channels, buffered channels, and directional channels.

The following is a sample code using a non-cache channel:

package main

import (
    "fmt"
)

func main() {
    c := make(chan int, 1)
    go func() {
        c <- 1
    }()
    fmt.Println(<-c)
}

In the above code, we use the make function to create a non-cache channel and define a coroutine to pass to and from the channel data. In the main function, we read the data in the channel through the "<-c" statement.

The characteristic of non-cache channel is that sending and receiving are synchronous, that is, two coroutines must be ready at the same time before sending and receiving operations, otherwise a deadlock will occur.

There is a difference between a cached channel and a non-cached channel. A cached channel can store multiple elements at the same time. The buffer size is the size initialized when the channel is created. When using a buffered channel, the sending operation will only block when the buffer is full, and the receiving operation will only block when the buffer is empty.

A directional channel can be used to control the read and write direction of the channel, for example, it can only be used to write data or can only be used to read data.

Conclusion

Golang synchronization methods include three types: mutex lock, rwmutex lock and channel. By using these synchronization methods, you can ensure that there will be no data access conflicts when multiple coroutines are executed concurrently. In actual development, programmers need to choose different synchronization methods based on actual scenarios to achieve optimal performance and reliability.

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