Cracking the answer: memory consumption of formal parameters in Go language

In the Go language, function parameters are passed by value, with the exception of pointer parameters, which will modify the pointed value and reflect it at the caller. When passing a pointer, additional memory needs to be allocated to store the pointer, which may cause memory consumption issues. This problem can be solved by passing a copy of the pointer by value, avoiding extra allocation.

Crack the answer: Detailed explanation of the memory consumption of Go language formal parameters

In the Go language, function parameters are passed by value. This means that the parameter values ​​passed to the function are copied inside the function, so any changes to the parameters will not affect the function caller. However, there is an exception when the argument is a pointer.

In this case, what is passed to the function is not a copy of the value, but a pointer to this value. This means that the function can modify the value pointed to, and these changes will be reflected in the function caller.

Although this feature is very useful, it also brings some potential memory overhead. Because the Go language must allocate additional memory for each function call to store pointers. This extra memory allocation can be a source of problems, especially when the function is called frequently and has a large number of arguments.

Practical case

The following code example demonstrates the impact of formal parameter pointers on memory consumption:

package main

import "fmt"

func main() {
    // 创建一个大型内存对象
    largeObject := make([]byte, 10000000)

    // 这个函数接受一个指针参数
    testFunction(&largeObject)

    // 测试函数执行后，释放内存对象
    largeObject = nil
}

func testFunction(p *[]byte) {
    // 访问通过指针传递的值
    fmt.Println(len(*p))
}

In this example, the testFunction function receives a Pointer to type []byte. When the function is called, it allocates additional memory to store the pointer to the largeObject. This additional allocation increases the program's memory consumption even if the largeObject is freed after the function returns.

To solve this problem, you can use passing pointers by value. This approach will create a copy of the pointer value for each function call, thus avoiding the creation of additional pointers. To do this, you can use the * notation in the function signature:

func testFunction2(*[]byte) {
    // 访问按值传递的指针副本
}

Conclusion

In the Go language, it is very important to understand the behavior of parameter passing, especially when passing pointer time. Passing a pointer by value results in additional memory allocation, which may affect the performance of your program. Therefore, it is recommended to avoid passing pointers when possible and instead pass a copy of the pointer by value.

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