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This article introduces how to optimize the Spring Boot project and JVM. The content is very detailed. Interested friends can use it for reference. I hope it will be helpful to you.

Project tuning

As an engineer, project tuning must be skillfully mastered. In Spring Boot projects, tuning is mainly done through configuration files and parameters of JVM.

1. Modify the configuration file

Regarding the modification of configuration file application.properties, it is recommended that "detailed profile modification document for Spring Boot project"

Https://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html#common-application-properties

The more important ones are:

Server.tomcat.max-connections=0 # Maximum number of connections that the server accepts and processes at any given time. Server.tomcat.max-http-header-size=0 # Maximum size, in bytes, of the HTTP message header. Server.tomcat.max-http-post-size=0 # Maximum size, in bytes, of the HTTP post content. Server.tomcat.max-threads=0 # Maximum number of worker threads. Server.tomcat.min-spare-threads=0 # Minimum number of worker threads.

2. JVM tuning

There is a guide on the JVM tuning Oracle official website, if you are interested, you can take a look at it. "description of JVM tuning on Oracle official website"

Https://docs.oracle.com/middleware/11119/wls/PERFM/jvm_tuning.htm#i1146060

3. JVM tuning actual combat

3.1 cases where the JVM parameter is not set

There is now a project that does not set any JVM parameters by default. Let me start and have a look.

Take a look at the stack allocation. The default maximum heap memory allocation is 8 gigabytes, which is obviously unreasonable.

3.2Let 's set the JVM parameter

For example, to configure a large number of parameters such as JVM:

-XX:MetaspaceSize=128m-XX:MaxMetaspaceSize=128m-Xms1024m-Xmx1024m-Xmn256m-Xss256k-XX:SurvivorRatio=8-XX:+UseConcMarkSweepGC

Mode one

If you are using development tools such as IDEA to start a running project, it is much easier to debug JDK. You just need to set the parameter value to VM Options.

After setting up successfully, my GC log and stack allocation have been OK. GC log:

Stack allocation:

Mode two

It is suitable for script or command line run-time settings at startup after the project is deployed. First package the project under the project path and clean up the old project:

$mvn clean

Package the new project:

$mvn package-Dmaven.test.skip=true

After the package is completed, enter the path where you can run the jar package:

Perform the operation of starting to set the JVM parameters:

$java-jar-XX:MetaspaceSize=128m-XX:MaxMetaspaceSize=128m-Xms1024m-Xmx1024m-Xmn256m-Xss256k-XX:SurvivorRatio=8-XX:+UseConcMarkSweepGC newframe-1.0.0.jar

At this time, if you look at the monitoring again, you will find that it is already OK. The stack is started according to the JVM parameter set at startup.

For information about the meaning of the JVM parameters for these settings, please refer to the tuning documentation given by Oracle earlier. I would like to say a few words here:

-XX:MetaspaceSize=128m (default metaspace size)-XX:MaxMetaspaceSize=128m (metaspace maximum)-Xms1024m (default heap size)-Xmx1024m (heap maximum size)-Xmn256m (Cenozoic maximum depth size)-XX:SurvivorRatio=8 (Cenozoic partition ratio 8:2)-XX:+UseConcMarkSweepGC (designated garbage collector, where the CMS collector is used)-XX:+PrintGCDetails (prints detailed GC logs)

Knowledge point

JDK8 then removed-XX:PermSize and-XX:MaxPermGen and replaced them with:

-XX:MetaspaceSize=128m (default size of metaspace)-XX:MaxMetaspaceSize=128m (maximum size of metaspace)

JDK8 begins to put the class's metadata in localized heap memory (native heap), an area called Metaspace, or metaspace in Chinese.

What are the benefits of using localized memory?

The most direct manifestation is that the java.lang.OutOfMemoryError: PermGen space problem will no longer exist. Because the default class metadata allocation is only limited by the size of local memory, that is, how much local memory is left, how much Metaspace can theoretically be, which solves the problem of insufficient space (it seems that the capacity is also related to the virtual memory of the operating system? It's not clear here.

However, it is obviously not realistic to make the Metaspace infinite, so we also want to limit the size of the Metaspace: use the-XX:MaxMetaspaceSize parameter to specify the size of the Metaspace area. By default, JVM dynamically sets the size of the MaxMetaspaceSize at run time as needed.

On how to carry out Spring Boot project optimization and JVM tuning to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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