Detailed explanation of memory allocation and storage location of variables in Golang program

Title: Detailed explanation of memory allocation and storage location of variables in Golang program

In Golang, variables are the basic unit for storing data in the program. When writing Golang programs, understanding the memory allocation and storage location of variables is very important to optimize program performance and avoid memory leaks. This article will delve into the memory allocation and storage location of variables in Golang programs, and provide specific code examples to help readers better understand.

1. Memory allocation of variables

In Golang, the memory allocation of variables mainly depends on their type. Variable types in Golang can be divided into basic types and composite types. Basic types include int, float, string, etc., and composite types include arrays, structures, interfaces, etc. Different types of variables are allocated in memory differently.

1.1 Memory allocation of basic type variables

For basic type variables, Golang determines the required memory space at compile time. For example, a variable of type int requires 4 bytes of memory space, and a variable of type float64 requires 8 bytes of memory space.

var num int
num = 10

In the above example, the value of variable num is 10, occupying 4 bytes of memory space.

1.2 Memory allocation of composite type variables

For composite type variables, Golang determines the required memory space based on the structure of the type at compile time. For example, a variable of structure type needs to occupy the sum of the memory space required by all its fields.

type Person struct {
    Name string
    Age  int
}

var p Person
p.Name = "Alice"
p.Age = 30

In the above example, variable p is a structure variable of type Person, and the memory space occupied is the length of the string Name plus the memory space occupied by Age of type int.

2. Storage location of variables

In Golang, the storage location of variables can be divided into two types: stack and heap. The stack is a last-in-first-out data structure used to store local variables and function parameters. Its allocation and release speed are fast. The heap is a data structure used to dynamically allocate memory and is used to store long-lived variables and data structures that need to be released manually.

2.1 Allocation on the stack

For basic type variables and small composite type variables, Golang usually allocates them on the stack. Variables allocated on the stack will be automatically released when the function completes execution, eliminating the need to manually manage memory.

func main() {
    var num int
    num = 10
    fmt.Println(num)
}

In the above example, the variable num is allocated on the stack of the main function. When the main function completes execution, the variable num will be automatically released.

2.2 Allocation on the heap

For large composite type variables and variables that need to exist for a long time, Golang usually allocates them on the heap. Variables allocated on the heap need to be manually managed and released when not needed, otherwise memory leaks will occur.

func main() {
    var p *Person
    p = &Person{Name: "Bob", Age: 25}
    fmt.Println(p.Name, p.Age)
    // 手动释放堆上分配的变量
    // 如果不手动释放，会造成内存泄漏
    p = nil
}

In the above example, the variable p is a pointer to the Person structure, and the Person structure is allocated on the heap. Manually set the variable p to nil in the program to release the corresponding memory space.

Conclusion

This article explains in detail the memory allocation and storage location of variables in Golang programs, and provides specific code examples to help readers better understand. When writing a Golang program, rationally allocating memory space for variables and selecting appropriate storage locations can improve program performance and reduce the risk of memory leaks. Hope this article can be helpful to readers.

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