What are the logging libraries in Go language?

With the continuous expansion of the scale of software systems, the logging mechanism has increasingly become an important part of system development. By recording detailed information during the operation of the software, developers can better understand the running status of the code. In order to detect and solve problems in time. Go language, as a powerful and efficient programming language, also provides many excellent logging libraries to support developers.

This article will introduce you to several commonly used Go language logging libraries, and briefly introduce their usage and characteristics. I hope it can help you with your logging work.

1. log package

The log package that comes with the Go language is a simple but full-featured log library with the following advantages:

• Support basic log printing function and provide Println, Printf, Print functions;
• You can specify the prefix of log output, log information output location and other options;
• You can control the output by setting the log level Level of detail.

Logging can be easily performed by calling the functions in the log package. For example:

log.Println("This is a log message.")

The output result is similar to:

2021/11/11 12:34:56 This is a log message.

Among them, the time in front of the output information is automatically generated and represents the time when the log is recorded.

2. zap

zap is a high-performance log library developed by Uber. Its main features include:

• Very fast, It also supports high-concurrency environments;
• You can configure log level, output format and other options;
• Provides a variety of log output methods, including console, file, network, etc.;
• Log fields can be flexibly customized to facilitate indexing and querying of large amounts of data.

Compared with the log package, the zap log library has faster output speed, stronger customizability, and richer functions. The following is a simple example of using zap to output logs:

package main

import (
    "go.uber.org/zap"
)

func main() {
    logger, err := zap.NewProduction()
    if err != nil {
        panic(err)
    }
    defer logger.Sync()

    logger.Info("This is a log message.", zap.String("key", "value"))
}

In this example, a zap logger is created and a piece of information is added to the log using the Info function. The second parameter zap.String("key", "value") specifies a field named key and sets its value to value. The output result is similar to:

{"level":"info","ts":1636634174.8175042,"caller":"main.go:9","msg":"This is a log message.","key":"value"}

It can be seen that the output log information contains multiple information fields such as log level, output timestamp, and program running context.

3. lumberjack

lumberjack is a simple log rotation library that helps developers rotate and limit file sizes when writing log files. Compared with outputting logs directly to files, using lumberjack can bring multiple advantages:

• It can automatically limit the size of log files to avoid overly large files that affect system operation;
• Log files can be rotated regularly according to time and other methods to facilitate future review of historical log information;
• can avoid competition problems in log files in a multi-threaded environment.

The following is an example of using lumberjack for log rotation:

package main

import (
    "github.com/natefinch/lumberjack"
    "log"
)

func main() {
    logger := &lumberjack.Logger{
        Filename:   "/var/log/myapp.log",
        MaxSize:    10, // megabytes
        MaxBackups: 3,
        MaxAge:     28, //days
    }

    defer logger.Close()

    log.SetOutput(logger)

    log.Println("This is a log message.")
}

In this example, a logger instance is used to record logs, and the path and file of the log file are specified in the Filename field. Name, MaxSize, MaxBackups, MaxAge specify the size, quantity, storage time and other options of the log file. Use the log.SetOutput function to set a logger instance to the default output location. The log file written in this way supports functions such as size limit and automatic rotation upon expiration.

Summary

Through the above introduction, we can know that the Go language provides a wealth of log libraries, and developers can choose different log libraries according to their own project needs. The most suitable for basic use is the log package, which can satisfy logging in most cases; for projects that require a large amount of log analysis and query, you can use the high-performance zap log library, which can effectively improve logging efficiency; logs need to be processed When rotating or limiting the size, you can consider using the lumberjack library to easily manage log files.

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