Is golang variable assignment atomic?

In golang, variable assignment is not atomic. The reason is: In concurrent programming, an atomic operation refers to an operation that will not be interrupted by other concurrently executing code during execution. The variable assignment operation may involve multiple steps, such as memory allocation, writing values, etc. These steps are not atomic.

The operating system for this tutorial: Windows 10 system, go1.20.1 version, Dell G3 computer.

In the Go language, variable assignment is not atomic.

In concurrent programming, atomic operations refer to operations that will not be interrupted by other concurrently executing code during execution. The variable assignment operation may involve multiple steps, such as memory allocation, writing values, etc. These steps are not atomic.

Therefore, in concurrent programming, if multiple goroutines assign values ​​to the same variable at the same time, it may cause race condition problems. In order to solve this problem, the Go language provides concurrency primitives such as mutex and atomic package to synchronize and protect when accessing shared variables.

The following is a sample code that demonstrates the situation when variable assignment is not atomic:

go

package main  
  
import (  
 "fmt"  
 "sync"  
)  
  
var (  
 counter int  
 mutex   sync.Mutex  
)  
  
func main() {  
 var wg sync.WaitGroup  
 for i := 0; i < 1000; i++ {  
 wg.Add(1)  
 go func() {  
 defer wg.Done()  
 mutex.Lock()  
 counter++  
 mutex.Unlock()  
 }()  
 }  
 wg.Wait()  
 fmt.Println(counter) // 输出结果可能不是1000，因为多个goroutine同时修改counter会导致竞态条件。  
}

In the above example, multiple goroutines simultaneously increment the counter variable by 1 The operation, since it is not protected by a mutex, can lead to a race condition. The output result may not be 1000. The specific result depends on the execution order and time of goroutine. In order to ensure the correctness of the counter variable, we use a mutex mutex to protect access to counter.

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