Shulou(Shulou.com)06/03 Report--

This article will explain in detail what the Java application performance tuning skills are, and the content of the article is of high quality, so the editor will share it with you for reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Most developers take it for granted that performance optimization is complex and requires a great deal of experience and knowledge. Well, it can't be said that this is completely wrong. Optimizing your application for best performance is not an easy task. But that doesn't mean you can't do anything if you don't have this knowledge.

1. Don't optimize until you know it's necessary.

This is probably one of the most important performance tuning techniques. You should follow common best practices and try to implement use cases efficiently. However, this does not mean that you should replace any standard libraries or build complex optimizations before you prove it necessary.

In most cases, premature optimization not only takes a lot of time, but also makes the code difficult to read and maintain. To make matters worse, these optimizations don't usually bring any benefits, because you spend a lot of time optimizing non-critical parts of the application.

So, how do you prove that you need to optimize something?

First, you need to define how fast the application code is, for example, to specify a maximum response time for all API calls, or to specify the number of records to import within a specific time frame. After doing this, you can measure which parts of the application are too slow and need to be improved. Then, move on to the second technique.

two。 Use the analyzer to find the real bottleneck

After you follow the first advice and determine that some parts of the application need to be improved, where do you start?

You can solve the problem in two ways:

Look at your code and start with the part that looks suspicious or that you think might cause a problem.

Or use the parser and get detailed information about the behavior and performance of each part of the code.

I hope I don't need to explain why I should always follow the second approach.

Obviously, the parser-based approach allows you to better understand the performance impact of your code and allows you to focus on the most critical parts. If you've ever used a parser, you must remember how surprised you were to find out which parts of the code had performance problems. To be honest, my first guess caused me to go in the wrong direction more than once.

3. Create a performance test suite for the entire application

This is another general tip that can help you avoid many of the unexpected problems that often occur after performance improvements are deployed to production. You should always define a performance test suite that tests the entire application and run it before and after performance improvements.

These additional test runs will help you identify the functional and performance side effects of the changes and ensure that they do not cause updates that do more harm than good. This is especially important if you work on components that are used by several different parts of the application, such as databases or caches.

4. Deal with the biggest bottleneck first

After creating a test suite and using the parser to analyze the application, you can list a series of issues that need to be addressed to improve performance. That's good, but it still doesn't answer the question of where you should start. You can focus on quick-impact solutions, or start with the most important questions.

Quick-impact solutions may be attractive at first because you can quickly show the first results. Sometimes, however, you may need to convince other team members or management that performance analysis is worth it-because you can't see the effect for the time being.

But overall, I suggest dealing with the most important performance issues first. This will provide you with the greatest performance improvement, and you may no longer need to solve some of these problems in order to meet your performance requirements.

This ends with common performance tuning techniques. Let's take a closer look at some Java-specific techniques.

5. Connect to String programmatically using StringBuilder

There are many different options to connect to String in Java. For example, you can use simple + or + =, as well as StringBuffer or StringBuilder.

So, which method should you choose?

The answer depends on the code that connects to the String. If you are adding new content to String programmatically, such as in a for loop, then you should use StringBuilder. It is easy to use and provides better performance than StringBuffer. Keep in mind, however, that StringBuilder is not thread-safe compared to StringBuffer and may not be suitable for all use cases.

You just need to instantiate a new StringBuilder and call the append method to add a new part to the String. After you have added all the parts, you can call the toString () method to retrieve the connected String.

The following code snippet shows a simple example. During each iteration, the loop converts I to a String and adds it to the StringBuilder sb along with a space. So, finally, this code will write "This is a test0 1 2 3 4 5 6 7 8 9" in the log file.

StringBuilder sb = new StringBuilder ("This is a test"); for (int item0; I

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