问题

atomic.StorePointer and atomic.LoadPointer are functions provided by the Go sync/atomic package for atomic operations on pointers.

In the first example, atomic.StorePointer is used to atomically store the pointer to the data variable in the memory location pointed to by p. Then, atomic.LoadPointer is used to atomically load the pointer value from p and cast it back to a string pointer before printing its value.

In the second example, the pointer is directly assigned to p without using atomic operations. The value is then loaded from p and cast to a string pointer before printing.

The difference between the two approaches lies in their atomicity. When using atomic.StorePointer and atomic.LoadPointer, the operations are guaranteed to be atomic, meaning they are indivisible and not subject to interference from other concurrent operations. This ensures that the value read or written is consistent.

If you decide to just read from a pointer directly, like in the second example, without using LoadPointer, there is a possibility of encountering race conditions. Race conditions occur when multiple goroutines access shared data concurrently without proper synchronization. In such cases, the value read from the pointer may be inconsistent or corrupted due to concurrent writes happening simultaneously.

To avoid race conditions and ensure data consistency, it is recommended to use atomic operations like atomic.LoadPointer and atomic.StorePointer when working with shared pointers in concurrent programs.

data := "abc"
atomic.StorePointer(&p, unsafe.Pointer(&data))
fmt.Printf("value is %s\n", *(*string)(atomic.LoadPointer(&p)))

data := "abc"
p = unsafe.Pointer(&data)
fmt.Printf("value is %s\n", *(*string)(p))

答案1

得分: 1

只要你只有一个goroutine访问该值，就不会出现问题。一旦你有多个goroutine，为了读取/写入最新值（而不是可能过时的CPU缓存中的值），你就需要原子访问。