Why is the log output in my Go program incorrect?

Using log output in Go language is a common debugging tool. When you debug your Go program, you may use log output to record variable values, logical flow and other information when the program is running, and analyze and debug this information. In practice, however, you may find that your program's log output is incorrect, or that there is no output at all. Why is this so?

In this article, I will introduce some reasons that may cause incorrect log output of Go programs and propose some solutions.

Problem 1: Incorrect log level

The log package of Go language provides 5 log levels: Debug, Info, Warning, Error and Fatal. By default, the log level of the log output is Info, that is, only log information of Info and above levels is output. If the logging output in your program is incorrect, it may be because you have set the wrong logging level.

Solution: Set the log output level through the SetOutput function. For example, if you want to output log information at Debug level and above, you can use the following code:

log.SetOutput(os.Stdout)
log.SetFlags(log.LstdFlags | log.Lshortfile)
log.SetLevel(logrus.DebugLevel)

Problem 2: The log output format is incorrect

Use the log package to output logs in the Go program , you can set the format of the log output through the SetFlags function. By default, the log output format is log message text. If the log output in your program is incorrect, it may be because you have set the wrong log output format.

Solution: Set the correct log output format through the SetFlags function. For example, if you want to display the time and file name and current line number when outputting the log, you can use the following code:

log.SetOutput(os.Stdout)
log.SetFlags(log.LstdFlags | log.Lshortfile)

Problem 3: The log is redirected to other places

In Go In your program, if you use multiple goroutines and output log information in them, then you must ensure that all output is correctly redirected to the same place. If one of your goroutines outputs log information but another goroutine does not receive the information, your log output may be incorrect.

Solution: Make sure all output is redirected to the same place. A common solution is to use logrus, which enables concurrency-safe logging output. For example, you can use the following code:

logrus.SetOutput(os.Stdout)
logrus.SetFormatter(&logrus.TextFormatter{})

Conclusion

Using log output in Go language can help you quickly locate problems in the program, but if your log output is incorrect, it will be wasted your time and energy. When designing your Go program, you must consider concurrency issues and ensure that your log output is properly redirected to the same place. At the same time, you must also follow certain rules when setting the log output level and format. As long as you use the appropriate techniques, you can more efficiently debug and troubleshoot problems while your program is running.

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