Memory allocation and recycling methods of Golang functions

Golang is an object-oriented programming language with its own garbage collection mechanism, so memory allocation and recycling are easier than other languages. In Golang, functions can also allocate memory and recycle memory. This article will introduce in detail the memory allocation and recycling methods of Golang functions.

1. Memory allocation of functions

When a function is declared, the program will allocate a memory for it to store the code and static variables of this function. When a function is called, the program allocates a stack memory to store the local variables and parameters of the call. The called function can allocate memory on the heap, but this is discouraged as it causes more GC pressure.

Let’s explain in detail how function parameters, return values ​​and local variables are allocated.

1. Allocation of parameters

The parameters and return values ​​of the function are agreed upon by the caller and the callee. When a function is called, the caller will This function allocates a memory to store parameters, which are passed to the callee via the stack. This memory will be automatically reclaimed after the call is completed.

2. Allocation of return value

The callee will store the return value in a separate memory after the function execution is completed. This memory is also allocated by the caller. of. Before the function returns, the callee will copy the return value from the function's stack frame to this memory, and then return the address of this memory. The caller will save this address in a register or stack for subsequent operations. After the call is completed, the caller will automatically reclaim this memory.

3. Allocation of local variables

When a function is called, the program will also allocate a piece of stack memory for storing the local variables of the call. This memory will also be automatically reclaimed after the function call ends. It should be noted that if the local variable is a pointer type and points to data on the heap, the pointer itself is allocated on the stack, and the data pointed to by the pointer is allocated on the heap.

2. Function memory recycling

Since Golang has its own garbage collection mechanism, function memory recycling is simpler than other languages.

After the function returns, the stack space allocated for local variables will be automatically reclaimed, and this block of memory will be marked as reusable and will be reused the next time the function is called. If a piece of data heap space is applied for inside a function, the programmer needs to manually release the piece of memory.

Let’s look at an example:

func main() {

data := make([]byte, 1024)
process(data)
// 这里的data会自动被GC回收

}

func process(data []byte) {

// 这里的data在函数返回后会自动被释放，无需程序员手动释放

}

In this example, the main function allocates a 1024-byte byte slice to the heap, and then passes the reference to the slice to the process function. The data variable in the process function is allocated on the stack and has nothing to do with the data in the main function. After the process function returns, the memory space corresponding to the data variable will be automatically reclaimed.

In addition to automatic recycling, Golang also provides some interfaces for manual memory recycling, such as runtime.GC() and runtime.FreeOSMemory(). But in general, there is no need to manually reclaim memory.

3. Summary

In Golang, the memory allocation and recycling of functions are completed automatically, and programmers can focus on the implementation of business code. However, it should be noted that if a piece of data heap space is applied for inside the function, the programmer needs to manually release the block of memory. When actually writing Golang programs, we should make full use of Golang's own garbage collection mechanism and try to avoid manually releasing memory.

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