SpringBoot Project Optimization and JVM Tuning Guide

As a backend engineer, mastering project optimization is essential. In SpringBoot projects, optimization is mainly performed by editing the application.properties file and adjusting JVM parameters.

1. Modify Configuration File – The official SpringBoot documentation lists important properties such as server.tomcat.max-connections=0 , server.tomcat.max-http-header-size=0 , server.tomcat.max-http-post-size=0 , server.tomcat.max-threads=0 , and server.tomcat.min-spare-threads=0 . Adjust these values according to your workload.

2. JVM Tuning – Oracle provides a comprehensive guide for JVM tuning ( link ). The article demonstrates the default JVM settings (e.g., 8 GB max heap) and shows why they are often unreasonable.

3. Practical JVM Tuning

3.1 Without JVM Parameters – Running the application with default settings results in an oversized heap allocation, as shown by the screenshots.

3.2 Setting JVM Parameters

Method 1 – IDE (e.g., IntelliJ IDEA) : Add the required options to the VM options field, such as:

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

After applying these options, the GC logs and heap allocation become normal.

Method 2 – Command Line : Package the project with Maven, then start it with the same JVM options:

java -jar myapp.jar \
  -XX:MetaspaceSize=128m \
  -XX:MaxMetaspaceSize=128m \
  -Xms1024m \
  -Xmx1024m \
  -Xmn256m \
  -Xss256k \
  -XX:SurvivorRatio=8 \
  -XX:+UseConcMarkSweepGC

Monitoring after launch confirms the parameters are effective.

4. Explanation of Key Parameters

-XX:MetaspaceSize=128m          # default Metaspace size
-XX:MaxMetaspaceSize=128m       # maximum Metaspace size
-Xms1024m                       # initial heap size
-Xmx1024m                       # maximum heap size
-Xmn256m                        # young generation size
-Xss256k                        # thread stack size
-XX:SurvivorRatio=8             # young generation survivor ratio (8:2)
-XX:+UseConcMarkSweepGC         # use CMS garbage collector
-XX:+PrintGCDetails             # print detailed GC logs

Note that since JDK 8, -XX:PermSize and -XX:MaxPermGen have been removed and replaced by Metaspace settings.

By following these steps, developers can efficiently tune SpringBoot applications for better performance and resource utilization.