Master the concurrency model and lock mechanism in Go language

Master the concurrency model and lock mechanism in Go language

With the rapid development of the Internet and the increasing needs of users, for high-performance and high-concurrency programming languages The demand is also getting higher and higher. As an open source programming language, Go language has become the first choice language for building high-concurrency programs with its efficient concurrency model and flexible locking mechanism.

1. Concurrency model

The Go language uses the lightweight thread mechanism Goroutine to achieve concurrency. Goroutine is a very lightweight thread that is scheduled at the bottom by the runtime of the Go language. It can be created by the Go keyword or started by the go keyword. Compared with the traditional thread model, Goroutine does not require explicit thread management, but is automatically managed by the runtime. Goroutine's scheduler uses a preemptive scheduling strategy, that is, each program fragment will be distributed as evenly as possible among different Goroutines, thereby achieving concurrent execution.

2. Concurrent programming

In the Go language, the most basic way to use concurrent programming is to start a new Goroutine by using the keyword go. The following is a simple sample code:

package main

import (
    "fmt"
    "time"
)

func main() {
    go printCount("Hello", 5)
    go printCount("World", 5)
    
    time.Sleep(time.Second * 2)
}

func printCount(word string, count int) {
    for i := 0; i < count; i++ {
        fmt.Println(word)
        time.Sleep(time.Millisecond * 500)
    }
}

In the above code, we use two goroutines to print "Hello" and "World" respectively. Each goroutine prints 5 times, and the two goroutines run at the same time. By adding time.Sleep, let the main goroutine wait for a period of time to ensure that both goroutines have enough time to run.

3. Locking mechanism

In concurrent programming, in order to ensure data synchronization between multiple goroutines, we usually need to use a locking mechanism. The Go language provides the sync package to support various lock mechanisms, including mutex (Mutex), read-write lock (RWMutex), etc.

Mutex lock is the simplest locking mechanism, which implements access control to shared resources through the Lock() and Unlock() methods. The following is a sample code for a mutex lock:

package main

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

var count int
var mutex sync.Mutex

func main() {
    for i := 0; i < 100; i++ {
        go increment()
    }
    
    time.Sleep(time.Second)
    fmt.Println("Count:", count)
}

func increment() {
    mutex.Lock()
    defer mutex.Unlock()
    count++
}

In the above code, we define a global variable count, and then use the mutex lock mutex to protect concurrent access to count. In the increment function, we use the Lock() method to acquire the lock, ensuring that only one goroutine can execute the function at a time, and then use the Unlock() method to release the lock. Through the use of mutex locks, we can ensure that the operation of count is safe, and the final output value of count is also correct.

In addition to mutex locks, the Go language also provides other lock mechanisms such as read-write locks (RWMutex) to more flexibly control the access of different goroutines to shared resources.

To sum up, the concurrency model and lock mechanism of Go language provide us with an efficient and safe way to handle concurrent programming. Mastering these features can help us better build highly concurrent programs and improve program performance and reliability.

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