Summarize some common golang wrong postures

Go language, as a relatively hot emerging language in recent years, has been widely used in network servers, distributed systems and other fields. Due to its simplicity, ease of learning and use, high concurrency, and powerful standard library support, more and more engineers choose to use Go for development. However, like any language, you may encounter various errors during use. This article will summarize some common golang error postures, hoping to help Go language developers better avoid and solve these problems.

1. Null pointer problem

The pointer in Go language defaults to nil during initialization. If it is used directly without assignment, a null pointer problem will occur. In a program, dereferencing a null pointer directly will cause the program to crash. A common solution is to make a judgment before using the pointer to determine whether it is a null pointer. The sample code is as follows:

var p *int
if p == nil {
    p = new(int)
}

2. String conversion problem

There are two ways to convert string types in the Go language. One is to convert the string into a byte array. The other is to convert the byte array into a string. If used improperly, it can cause all kinds of strange problems in the program.

1. Convert string to byte array:

s := "hello world"
b := []byte(s)

2. Convert byte array to string:

b := []byte{104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100}
s := string(b)

Need to pay attention What is important is that when converting a byte array into a string, the byte array must be in UTF-8 encoding format, otherwise garbled characters or decoding failure will occur.

3. Problems caused by defer statements

The defer statement in Go language can be used to register function calls, and these functions will be executed sequentially when the function returns. Although this feature is very useful, you should also be careful to avoid some hard-to-find problems when using it.

Consider the following code:

func foo() (err error) {
    defer func() {
        if err != nil {
            fmt.Println("defer recover: ", err)
            err = nil
        }
    }()
    return errors.New("bar")
}

In this code, panic is captured in the defer statement and the return value err is modified to nil. However, the above code does not have the expected effect. Go's return statement has already assigned the return value to the corresponding variable during compilation, and the modification of the variable with the same name in defer will not affect the assigned return value. Therefore, the above code will return a non-nil error object instead of nil, causing the caller to be unable to handle the return value correctly.

The common way to solve this kind of problem is to use named return values, that is, specify a name for the return value when the function is defined, and modify the name directly inside the function:

func foo() (err error) {
    defer func() {
        if err != nil {
            fmt.Println("defer recover: ", err)
            err = nil
        }
    }()
    err = errors.New("bar")
    return
}

4. Concurrency issues

Go language, as a language, supports concurrency when designed, making it very simple to write high-concurrency programs. However, improper use can also cause problems.

goroutine and channel in Go language are two key concepts of concurrent programming. When using, you should pay attention to the following points:

1. Avoid concurrent access to shared memory: When multiple goroutines modify the same variable concurrently, a race condition will occur, causing the program's behavior to become Very uncertain. At this time, mechanisms such as locks or atomic operations should be used to ensure memory consistency.
2. Avoid deadlock: When using channels, care should be taken to avoid deadlock situations. Deadlock is usually caused by the channel's send and receive not pairing. When writing code, you should develop good habits to ensure that send and receive operations occur in pairs.

5. Package import issues

The import statement is used in Go language to import other packages. If used improperly, it will also cause some problems.

1. Import unnecessary packages: When writing code, you should develop good habits and only import the packages you need to use. If unnecessary packages are imported, the complexity and memory usage of the program will increase.
2. Circular dependency problem: When there are circular dependencies between packages, the compiler will not be able to compile normally. At this point, mechanisms such as interfaces should be used to resolve dependencies.

This article summarizes some common mistakes in Go language development, including null pointer problems, string conversion problems, problems caused by defer statements, concurrency problems and package import problems, etc. I hope these summaries can help Go language developers better use this powerful language and write better code.

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