3、 High quality programming and performance tuning practical youth training camp notes

High quality programming and performance tuning | Youth Camp notes

This is my participation 「 The third youth training camp - Back end field 」 The third part of note creation activities 3 Notes

High quality principle ：1、 simplicity 2、 Readability 3、 Productivity

Annotation specifications

Code is the best comment , Comments should provide context information that the code does not express , Common symbols should always be annotated

• Comments should explain what the code does
• Comments should explain how the code does
• Comments should explain why the code is implemented
• Comments should explain what goes wrong with the code

Naming specification

Variable naming

• Contains the amount of information about variable names
• It has a specific meaning
• Avoid passing in wrong values , Cause unexpected errors

Function name

• Do not carry the context information of the package name

• Be as brief as possible

  eg：

  

Package name naming

• It's just small letters . Does not contain characters such as uppercase letters and underscores
• Contains certain context information
• It does not have the same name as the standard library .

Coding standards

Control process

• Avoid nesting
  If if else Both branches of contain return sentence , Then redundant... Can be removed else Convenient for subsequent maintenance ,else Generally, it is a normal process , If it is necessary to add judgment logic in the normal process , Avoid branch nesting

  

• Prioritize errors and special situations , Return early or continue the loop to reduce nesting

Error and exception handling

Simple error

• priority of use errors.New To create anonymous variables to directly represent simple errors
• If there is a need for formatting , Use fmt.Errorf

Complex error （Wrap and Unwrap）

​ Wrap Provides a error Nest another error The ability of , To create a error Tracking chain

​ stay fmt.Errorf Use in ：%w Keyword to associate an error to the error chain

Wrong judgment

• Specific errors ： Use errors.Is To determine whether it is a specific error . Different from using ==, Using this method, we can determine All errors in the error chain Whether there are specific errors

• Certain kinds of errors ： Get a specific kind of error on the error chain , Use errors.As

panic( Be careful ！ I always use in projects )

• Only for really abnormal situations

• Not recommended （ When an irreversible error occurs during the start-up phase of the program , Can be in init or main Use in a function panic）

recover

• recover Effective range , At present goroutine The quilt of defer The nesting that takes effect in the function of cannot take effect

• defer The statement is last in, first out

• The common situation is to record panic Call stack information , When problems occur, it is convenient to analyze and locate . If you need more context information , Sure recover In the after log Record the current call stack

performance optimization （Benchmark Tools ）

slice Use advice

​ slice Pre allocated memory , Estimated space

• Try to use make() Provide capacity information when initializing slices , Avoid multiple expansions （ Because we need to open up a larger space in memory to store and copy , It's a waste ）
• You can use copy Instead of creating a new slice（ Avoid the huge space occupied by calling the original slice , The large memory of the original slice cannot be released ）

map Use advice

​ Pre allocated memory , Estimated space , To reduce memory copies and Rehash Consume

string manipulation

​ Among the three string splicing methods ,strings.Builder The fastest ,bytes.Buffer secondly ,+ The slowest

​ When using + Splicing 2 A string , Generate a new string , We need to open up a new space , The size of the new space is the sum of the size of the original two strings . When splicing the third string , Open up a new space 、 The size of the new space is the sum of the sizes of the three strings , And so on

​ and strings.Builder,bytes.Buffer The bottom is []byte Array memory expansion strategy , There is no need to reallocate memory every time you splice

Empty structure

​ Empty structures do not occupy memory space , Can be used as a placeholder

• Realization Set, Consider using map Instead of
• For this scenario , Just use map Key , You don't need a value
• Even if it's going to be map Is set to bool type , Will occupy more 1 Byte space

atomic The difference between bag and lock

• The lock is realized through the operating system , It's a system call

• atomic The operation is realized by hardware , It's more efficient than a lock

• sync.Mutex It should be used to protect a piece of logic , Not just to protect a variable

• For non numeric operations , have access to atomic.Value, Can carry a interface{}

performance tuning

principle

• Rely on data, not speculation
• Locate the biggest bottleneck rather than the details
• Don't optimize too early
• Don't over optimize

Performance analysis tool pprof

do , have access to atomic.Value, Can carry a interface{}

performance tuning

principle

• Rely on data, not speculation
• Locate the biggest bottleneck rather than the details
• Don't optimize too early
• Don't over optimize

Performance analysis tool pprof

Official documents ：https://blog.wolfogre.com/posts/go-ppof-practice/