Detailed explanation of JVM garbage collection strategy for Java server performance optimization

JVM garbage collection strategy

Java virtual machine (JVM) is the basis for Java programs to run, and garbage collection (GC) is one of the core mechanisms for JVM to manage memory. The selection and optimization of garbage collection strategies have a direct impact on Java server performance.

This article will explore the basic principles of JVM garbage collection, introduce several common garbage collection strategies, and provide some optimization suggestions.

The basic principles of garbage recycling

In Java, memory management is mainly performed automatically through the garbage collector.

The main task of the garbage collector is to identify objects that are no longer in use and free up the memory they occupy.

The JVM divides memory into several areas, the most important of which are the heap and method area.

Common garbage collection strategies

• Serial GC
• Serial GC is the most basic garbage collection strategy, which uses single thread for garbage collection and is suitable for single-core processors or small applications.

-XX:+UseSerialGC

• Parallel GC
• Parallel GC, also known as the throughput priority collector, uses multithreading for garbage collection to improve the efficiency of garbage collection.

-XX:+UseParallelGC

• Concurrent Mark Sweep (CMS) GC
• CMS GC attempts to minimize pauses during garbage collection, which is achieved by concurrent tagging and scrubbing.

-XX:+UseConcMarkSweepGC

• G1 GC
• G1 GC is a garbage collection strategy for regionalized heaps, which divides the heap into multiple areas and prioritizes the area with the most garbage.

-XX:+UseG1GC

Choosing garbage collection strategy

• Choosing the appropriate garbage collection strategy depends on the characteristics and performance requirements of the application.
• For example, for applications that need to minimize pause time, CMS GC can be selected, while for applications that pursue high throughput, Parallel GC or G1 GC can be selected.

Garbage recycling parameter tuning

• Heap size settings
• Set the heap size reasonably according to the application's memory requirements.

-Xms1024m -Xmx1024m

• The ratio of the new generation to the old generation
• Adjusting the size ratio of the new generation and the elderly can affect the frequency and efficiency of garbage recycling.

-XX:NewRatio=2
-XX:SurvivorRatio=8

• GC Log
• Turning on GC logs can help monitor and analyze garbage collection performance.

-XX:+PrintGCDetails
-XX:+PrintGCDateStamps

Example: Optimize performance with G1 GC

Here is an example of using G1 GC and doing basic tuning.

package ;

public class GcOptimizationExample {
    public static void main(String[] args) {
        // Simulate long-running services        while (true) {
            // Simulate business logic        }
    }
}

When starting the JVM, you can set the following parameters to enable G1 GC and tune it:

java -XX:+UseG1GC -XX:G1HeapRegionSize=16m -XX:MaxGCPauseMillis=100 -XX:+PrintGCDetails -XX:+PrintGCDateStamps -jar 

Monitoring and analysis tools

Using tools such as VisualVM, JConsole, or commercial tools such as New Relic, AppDynamics can help monitor the performance of the JVM, including garbage collection activities.

in conclusion

Garbage collection is one of the key factors affecting Java server performance. By selecting the right garbage collection strategy and carefully tuning, the performance and response speed of the application can be significantly improved. Continuous monitoring and analysis of garbage collection activities is an important step in ensuring application stability and performance.

The above is personal experience. I hope you can give you a reference and I hope you can support me more.